If your main goal for a quiz is to generate as many ad views as possible, you need a way for the Riddle unit to tell your ad units to reload. The Riddle unit is an isolated iFrame and proceeding to the next question normally has no effect on the surrounding page. Initiating a full page reload is also not a good idea as that would also reload the Riddle unit.
You therefore need to listen to Riddle events and use these events to tell your ad units to reload.
Here is an example of how this works, just answer the questions in this quiz and watch the ad unit reload.