An antonym could be prior knowledge<span />
The foot-in-the-door method is basically a psychological method where you ask for a small request first, then a bigger one later. So I think it's A, just because the others don't work. B is just straight up asking for a big favor, C is providing you with the "must-do" effect, and D is simply a favor for a favor.
2. we removed the training wheels from my younger sisters bike
hope this helped (:
Bias? is it used like author's bias?
