Quiz not allowing student to select answer choice in quiz

Alternatively, I just encountered another case where we weren't able to select the radio buttons, and it has happened often in the past. It appears that the radio button selections were located at the bottom of the slide and partially obscured by the invisible surface area of the textbox directly above them.

So, maybe try selecting the multiple-choice object and moving it to the top of the slide. It's such an easy issue, but one that could go unnoticed, I think. :)