I understand why all other answers are wrong, but D threw me off because the AC D says the identical twins were acting differently just "to differentiate themselves from each other" - which felt to me like this is proof that the twins overcompensating for a strong genetic similarity - thus not weakening the argument. Am I totally off here?

Confused why the premise is mapped bulge --> broken joist, if "only" is a group two indicator, and the broken joist is causing the bulge, not the other way around?

Very confused why Q3 sentence one has "pure heart" as the necessary condition, rather than the sufficient...

I'm interested, please add me to the group