Which of these phrases is the most objective? a. my mother taught italian lessons at the community center. b. the music my stupid sisters listened to was annoying. c. our family used to get together all the time with this crazy greek family. d. my oldest sister was a real pain sometimes.

The sentence which is the most objective is A. My mother taught Italian lessons at the community center.
It is a fact, therefore it is objective. The other sentences are somebody's opinions - stupid sisters, crazy Greek family, a real pain - these words show that it is someone's opinion, which is subjective, not objective.

I’m guessing it’s true