A B?

Took my math test last night - last one before the final next week - waited for my grade. 89% B! I don't accept B's and you want to know the real kicker!?! One question asked if a problem is "communative" Now I know it is Commutative - I just assumed it was a slip of the fingers, a typo, a wire didn't connect in translation type of thing - but NO - it was a "trick" question worth 5 points. I don't understand why instructors feel like they have to try and pull a fast one on the students, LOSERS! He's messing with my 4.0, I am NOT happy.