Multiple choice question with figure choices gives error when used with \printanswers command in exam class

Question

This question has been modified from this question with added feature. However, when I used \printanswers command, the code gives an error the following error:

! Extra }, or forgotten \endgroup.
\endmulticols ->\par \if@boxedmulticols \egroup 
                                                \balance@columns \return@non...
l.24             \end{multicols}

?

My MWE code modified with suggestion from Gonzalo Medina when used with \noprintanswers is given below:

\documentclass{exam}
\usepackage{multicol}
\usepackage{graphicx}
\usepackage{adjustbox}
%\printanswers
\noprintanswers
\begin{document}
\begin{questions}
    \question 
    \begin{minipage}[t]{0.65\linewidth}
    Consider the network graph shown in the figure, which of the following is NOT a \textit{tree} of this graph?
            \begin{choices}
        \begin{multicols}{2}
                \choice
                    \adjustbox{valign=t}{\includegraphics[scale=0.2]{example-image-a}}
                \choice
                    \adjustbox{valign=t}{\includegraphics[scale=0.2]{example-image-b}}
        \end{multicols}\par
        \begin{multicols}{2}
                \choice
                    \adjustbox{valign=t}{\includegraphics[scale=0.2]{example-image-c}}
                \CorrectChoice
                    \adjustbox{valign=t}{\includegraphics[scale=0.2]{example-image-a}}
        \end{multicols}
            \end{choices}
\end{minipage}\hfill%
    \begin{adjustbox}{minipage={0.30\linewidth},valign=t}
    \includegraphics[width=\linewidth]{example-image-a} 
\end{adjustbox}
\end{questions}
\end{document}

When \printanswers command is used, it should give the output like this highlighting the partlabel corresponding to the \CorrectChoice:

Any suggestion to solve the error when used \printanswer command in the given code!

Ther other answer to your previous question works in this case too. Is there any reason you don't want to use it? — , Oct 11 '15 at 02:55
Have you tried @HarishKumar's answer? In your comment on the other answer to your other question, you don't make this clear. Presumably you'd at least get a different error in that case? — cfr, Oct 11 '15 at 02:57
I will see to it Harish. I wanted minimum changes to the original code and found convenient to use with what Gonzalo has suggested. It proved good and working as long as I use \noprintanswers command to the code. But it results an error when I put \printanswers command. — Khaaba, Oct 11 '15 at 02:59
This happen only if \CorrectChoice is last. In this case you can try with\CorrectChoice\endgroup. — touhami, Oct 11 '15 at 05:58

touhami · Accepted Answer · 2015-10-11T15:31:43.110

Updated In this solution, we define new environment multichoices that works like multicols, by defaut it hase two columns but one can set more if needed.

\makeatletter
\newenvironment{multichoices}[1][2]{%
\begin{multicols}{#1}}{%
\if@correctchoice \endgroup \fi
\end{multicols}}
\makeatother

MWE

\documentclass{exam}
\usepackage{multicol}
\usepackage{graphicx}
\usepackage{adjustbox}
\printanswers
%\noprintanswers

\makeatletter
\newenvironment{multichoices}[1][2]{%
\begin{multicols}{#1}}{%
\if@correctchoice \endgroup \fi
\end{multicols}}
\makeatother

\begin{document}
\begin{questions}
    \question 
    \begin{minipage}[t]{0.65\linewidth}
    Consider the network graph shown in the figure, which of the following is NOT a \textit{tree} of this graph?
            \begin{choices}
        \begin{multichoices}
                \choice
                    \adjustbox{valign=t}{\includegraphics[scale=0.2]{example-image-a}}
                \choice
                    \adjustbox{valign=t}{\includegraphics[scale=0.2]{example-image-b}}
        \end{multichoices}\par
        \begin{multichoices}
                \CorrectChoice
                    \adjustbox{valign=t}{\includegraphics[scale=0.2]{example-image-a}}
                \choice
                    \adjustbox{valign=t}{\includegraphics[scale=0.2]{example-image-c}}
        \end{multichoices}
            \end{choices}
\end{minipage}\hfill%
    \begin{adjustbox}{minipage={0.30\linewidth},valign=t}
    \includegraphics[width=\linewidth]{example-image-a} 
\end{adjustbox}


    \question 
    \begin{minipage}[t]{0.65\linewidth}
    Consider the network graph shown in the figure, which of the following is NOT a \textit{tree} of this graph?
            \begin{choices}
        \begin{multichoices}
                \choice
                    \adjustbox{valign=t}{\includegraphics[scale=0.2]{example-image-a}}
                \choice
                    \adjustbox{valign=t}{\includegraphics[scale=0.2]{example-image-b}}
        \end{multichoices}\par
        \begin{multichoices}
                \choice
                    \adjustbox{valign=t}{\includegraphics[scale=0.2]{example-image-c}}
                \CorrectChoice
                    \adjustbox{valign=t}{\includegraphics[scale=0.2]{example-image-a}}
        \end{multichoices}
            \end{choices}
\end{minipage}\hfill%
    \begin{adjustbox}{minipage={0.30\linewidth},valign=t}
    \includegraphics[width=\linewidth]{example-image-a} 
\end{adjustbox}

    \question 
    \begin{minipage}[t]{0.65\linewidth}
    Consider the network graph shown in the figure, which of the following is NOT a \textit{tree} of this graph?
            \begin{choices}
        \begin{multichoices}
                \choice
                       bla bla
                \choice
                       bla bla
        \end{multichoices}\par
        \begin{multichoices}
                \choice
                       bla bla
                \CorrectChoice
                    bla bla
        \end{multichoices}
            \end{choices}
\end{minipage}\hfill%
    \begin{adjustbox}{minipage={0.30\linewidth},valign=t}
    \includegraphics[width=\linewidth]{example-image-a} 
\end{adjustbox}


    \question 
    \begin{minipage}[t]{0.65\linewidth}
    Consider the network graph shown in the figure, which of the following is NOT a \textit{tree} of this graph?
            \begin{choices}
        \begin{multichoices}
                \choice
                       bla bla
                \choice
                       bla bla
        \end{multichoices}\par
        \begin{multichoices}
                \CorrectChoice
                       bla bla
                \choice
                    bla bla
        \end{multichoices}
            \end{choices}
\end{minipage}\hfill%
    \begin{adjustbox}{minipage={0.30\linewidth},valign=t}
    \includegraphics[width=\linewidth]{example-image-a} 
\end{adjustbox}

\end{questions}
\end{document}

Touhami, can you please add another question in which choices are texts only along with this figure choices? Code runs but correctchoice label is missing when I use \printanswers command? May be I need little more understanding of the tricks you have provided. — Khaaba, Oct 11 '15 at 07:50
it worked without the aforementioned error in the original question with tikzpicture environment instead of includegraphics. Now after the recent update, I have started getting the aforementioned error with tikzpicture: ! Extra }, or forgotten \endgroup. I can't get a clue to fix it. Could you please help me? — Khaaba, Sep 25 '18 at 16:05

Multiple choice question with figure choices gives error when used with \printanswers command in exam class

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