You can use $G->{correct_ans} for the string, $G->{correct_ans_latex_string} for the TeX version, or $G->{original_formula} for the Formula() object for the expression.
WeBWorK Problems
MathObject List answers are displaying the value, not the name, of items in the list
This forum has a limit to the number of forum postings you can make in a given time period - this is currently set at 10 posting(s) in 1 day