I didn't find any way to do this in the manual for the exam
class, so I made a quick custom solution that prints a list of answers automatically. The only thing that you must do is to use \CC
for the correct choice, and then write \printmyanswers
to display the answers as a list. There are some examples on this site for the tabular, but it's pretty verbose and I'm not sure it's worth it.
I put the answers in the same page, but you can simply add a \newpage
before the command, for example.
Output

Code
\documentclass{exam}
\usepackage{pgffor}
\newcounter{solcount}
\setcounter{solcount}{1}
\newcommand\CC{%
\CorrectChoice\label{sol:\arabic{solcount}}
\stepcounter{solcount}
}
\newcommand\printmyanswers{%
\section*{\centering Answers Sheet}
\foreach \x in {1,...,\thequestion}{%
\noindent
\x.~\ref{sol:\x}\par
}
}
\begin{document}\noindent
\begin{questions}
\question This is a multiple choice question
\begin{choices}
\choice this is a choice
\choice this is another choice
\CC this is the correct choice
\choice this is another choice
\end{choices}
\question This is a multiple choice question
\begin{choices}
\choice this is a choice
\CC this is the correct choice
\choice this is another choice
\choice this is another choice
\end{choices}
\end{questions}
\printmyanswers
\end{document}