I was wondering if one could use a LaTeX \ifXXX to check if a the catalog or answers option is set,
such that I can include the answers for open questions in the question source files.

This would be help full to not only to have the questions but the answers in the same file too.

I would use it something along the line
<pre>
\ifAMCAnswers
the answer (text, picture, table or whatever)
\else
the open space to be used by the student or a figure to be completed etc.
\fi
</pre>