[JumpCrisscross]

> Or maybe it's just that you need to pick something, so why not C?

Mostly this. That said, one definitely picks up when teachers bias the dice.

Some want an even distribution. If you confidently answered C's and D's early on and were later forced between A and C, A was the lucky bet. Other teachers avoided the first and last choices like the plague; this was common. With them, B and C (on a four-choice test) were the lucky bets.