Which sentence is written correctly?

I believe the answer of this problem is A. All other answers don't need the hyphen or do. I hope this answer helps you!
Answer:
A) The doctor prescribed me an anti-inflammatory drug.
Explanation:
The words Trimester and Disbelief do not need a hyphen. They stand on their own all together. The word ex-mayor, though, is actually the word maior with the prefix ex- that is commonly used with a hyphen: ex-girlfriend, ex-husband, ex-volunteer, and so on.