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ans1 =1 means the first answer choice in the upper code box is the correct one.
In multiple choice the ans1= in the code box has to be the choice with the correct answer (ie, ans1 = 1; instead of ans1 = a1;), not what's being called (which is vastly different than free response).
Pro tip: just make a precursor ans = expression on how to calculate the answer. In the upper TeX box, in choice 1 put in ans, and in the bottom Code box, ans1=1.
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