To make clean breast of

Answer: Option C

The correct answer is (C): To confess without reserve.

The idiom "to make a clean breast of" means to confess everything, to tell the whole truth, without holding anything back.

Think of it as clearing your chest (breast) of a burden, a secret, or something you've been hiding. You're being completely open and honest.

Option A (To gain prominence) is about becoming famous or important, which doesn't relate to confessing.
Option B (To praise oneself) is about boasting, the opposite of admitting wrongdoing.
Option D (To destroy before it blooms) refers to stopping something before it can develop, also unrelated.
Option E (None of these) is incorrect since option C is the right answer.

Therefore, "to confess without reserve" is the most accurate explanation of the idiom "to make a clean breast of".