In principle, yes they could turn on Design Mode or run a macro to reveal what is in a Content Control but...

The example document you loaded actually doesn't lend itself to a person doing the test in Word - put yourself in their position and work out how you would indicate the right answer. It looks like it needs to be printed out and the student uses a pen to circle or tick their answers.

If you wanted them to be using an electronic version in Word you should be putting checkboxes next to every possible answer to make it possible for them to answer the questions quickly. If you did that, the code would likely need to be modified to not touch the checkboxes (which are also CCs). It would actually be conceivably possible to create a macro to automatically score a test if that was done.

__________________
Andrew Lockton
Chrysalis Design, Melbourne Australia