Sometimes I don't concentrate enough because I'm in a hurry or bored. Sometimes you "correct" answers could be questioned. For this, I don't progress in reading comprehension skills and I'm even more bored. Please integrate a button to disactivate a "wrong" answer if the user feels that this error should not lead to repetions or less progress.
Example: Susie asks about 'flexible working hours' after the birth of her (hypothetical) baby. That doesn't mean necessarily, that she want's to work less ours, as you expect as "right" answer. If I could label my wrong answer with such a "I don't mind-button", you could automatically search for questions to reconsider (if many users press this button) and the user wouldn't feel blocked.

Yours sincerly