Here is an option that allows you to tailor the alignment of multiple choices and spread them to suit your needs:

\documentclass{article}
\usepackage{environ,enumitem,amsmath,xkeyval,expl3}
\ExplSyntaxOn
\cs_new_eq:NN \calc \fp_eval:n
\ExplSyntaxOff
\newlist{question}{enumerate}{1}
\setlist[question]{label={\arabic*)}}
% http://tex.stackexchange.com/q/127005/5764
\makeatletter
\define@key{mc}{choices}{\setlength{\mchoicewidth}{\dimexpr\calc{1/#1}\linewidth}}
\define@boolkey{mc}{resume}[true]{}
\define@choicekey*{mc}{align}[\val\nr]{left,center,right}{%
\expandafter\global\expandafter\let\expandafter\mc@align
\ifcase\nr\relax% left
\raggedright
\or% center
\centering
\or% right
\raggedleft
\fi
}
\newcounter{multiplechoice}
\renewcommand{\themultiplechoice}{\Alph{multiplechoice}}
\NewEnviron{multiplechoice}[1]{%
\par\nobreak
\setkeys{mc}{choices=5,resume=false,align=left,#1}%
\ifKV@mc@resume\else
\setcounter{multiplechoice}{0}%
\vspace{\bigskipamount}%
\fi
\setlength{\parindent}{0pt}%
\def\item##1\item{\dosomething{##1}}%
\expandafter\@empty\BODY\item}
\newlength{\mchoicewidth}
\newcommand{\dosomething}[1]{%
\def\ampora@arg{#1}%
\ifx\ampora@arg\ampora@stop
\expandafter\env@ignore % to end the recursion
\else
\refstepcounter{multiplechoice}%
\begin{tabular}[t]{@{}p{\mchoicewidth}@{}}
(\themultiplechoice)\nobreakspace
\mc@align #1
\end{tabular}%
\expandafter\item % to continue the recursion
\fi
}
\edef\ampora@stop{\noexpand\env@ignore\space}
\makeatother
\begin{document}
\begin{question}
\item Solve for $x$: $x = \cfrac{1}{2 - \cfrac{1}{2 + \cfrac{1}{2 - \cfrac{1}{2 + \ddots}}}}$
\begin{multiplechoice}{}
\item $\sqrt{2}$
\item $\dfrac{\sqrt{5}-1}{2}$ %CORRECT
\item $\dfrac{1+\sqrt{5}}{2}$
\item $\dfrac{1}{\sqrt{3}}$
\item NOTA
\end{multiplechoice}
\item Solve for $x$: $x = \cfrac{1}{2 - \cfrac{1}{2 + \cfrac{1}{2 - \cfrac{1}{2 + \ddots}}}}$
\begin{multiplechoice}{choices=3,align=center}
\item $\sqrt{2}$
\item $\dfrac{\sqrt{5}-1}{2}$ %CORRECT
\item $\dfrac{1+\sqrt{5}}{2}$
\end{multiplechoice}
\begin{multiplechoice}{choices=2,resume,align=center}
\item $\dfrac{1}{\sqrt{3}}$
\item \raggedleft NOTA
\end{multiplechoice}
\end{question}
\end{document}
The multiplechoice environment provides a key-value mandatory argument where you can set the number of choices (default is 5), whether you want the environment numbering to resume from a previous one, as well as the generic alignment of each item. You can override individual items alignment as needed using, for example,
\begin{multiplechoice}{..}
\item ...
\item \raggedleft <some item>
\item ...
\end{multiplechoice}