The problematic question is "have you participated in sexual activities that constitute statutory rape?" The issue is that in some jurisdictions, a 17 year old with a 20 year old is statutory rape, while in others, it's not. If the question were "that constitute statutory rape in the relevant jurisdiction", you could have two people who've done exactly the same thing but only one losing a purity point. If we choose a specific jurisdiction - well, which? Or we could define statutory rape ourselves. Or we could avoid the hassle and bring in a completely different question that won't cause this problem in the first place!