MCQ Answer
A. She is a great singer, but she is also a great dancer.
B. I went to the store and bought some milk.
Correct
Explanation
Option B uses a compound predicate ('went... and bought') rather than two full independent coordinate clauses joined by a comma and coordinator.
C. I love reading books, and I also love writing stories.
D. He is a good teacher, but his classes are boring sometimes.
Correct Answer
I went to the store and bought some milk.