Mary made a clean breast of everything. This means that Mary

Analyze the question: The question asks for the meaning of the idiom "to make a clean breast of (something)."

Explain the concept: An idiom is a fixed expression whose meaning cannot be worked out from the individual words. "To make a clean breast of something" means to confess fully and honestly, holding nothing back. The "breast" stands for the heart or conscience, and "clean" means free of hidden guilt. So, to make a clean breast is to unburden yourself by telling the whole truth.

Solution, step by step:

1. "Made a clean breast of everything" means Mary confessed everything.
2. Check each option: • A. won everyone over: This means persuading people to support her. It has nothing to do with confession. ✗ • B. told the whole truth: This matches the idea of a full confession. ✓ • C. did everything efficiently: This is about skill or speed, not honesty. ✗ • D. changed the way things were done: This is closer to "turned over a new leaf" or "made reforms." ✗

Answer: Option B.

Tip: In idiom questions, look for the "confess/admit" family of meanings.

• Come clean = confess
• Spill the beans = reveal a secret
• Make a clean breast of = confess fully

Picture someone "clearing their chest" of a heavy secret, and you will remember it easily.