"Ebullient'' means cheerful and full of energy.
Step 1: Analyze options
- (A) Foolish: lacking good sense or judgment.
- (B) Filthy: very dirty.
- (C) Depressed: in a state of unhappiness or despondency.
- (D) Gentle: mild in temperament or behavior.
Step 2: Find opposite meaning
The opposite of being cheerful and energetic is being sad or low in spirits, i.e., "Depressed'' (option C).