Height of enumerate items in multicols environment for proper alignment

Question

For some problem sheets I have been using the shortenumerate package with hardcoded widths for the columns so far and I wanted to use multicols instead which is a lot easier to use. However the enumerate items on the left are not aligned with the ones on the right - in my example below there is a fraction on the right which takes more height than the left (a) equation and the interval in (e) takes a lot more space than the equation (f) simliarly to the second line with (c) and (d). As such I was wondering whether there is a possibility to use the same height throughout the enumeration to align everything properly.

\begin{multicols}{2}
    \begin{enumerate}
        \item[(a)] $\displaystyle f(x)=2x^7-x^5+6x+1$, $D=\mathbb{R}$           
        \item[(c)] $\displaystyle f(x)=\sqrt{x}$, $D=[0,\infty)$            
        \item[(e)] $\displaystyle f(x)=\tan(x)$, $\displaystyle D=\left(-\frac{\pi}{2},\frac{\pi}{2}\right)$            
        \item[(b)] $\displaystyle f(x)=\frac{x+1}{x^2+x+7}$, $D=\mathbb{R}$
        \item[(d)] $f(x)=\sin(x)\exp\left(\left (x+1\right )^2\right)$, $D=\mathbb{R}$
        \item[(f)] $\displaystyle f(x)=2^x$, $D=\mathbb{R}$
    \end{enumerate}
\end{multicols}