Despite years of public speaking practice, Sarah remained notably _____ in front of large crowds, often speaking in a low voice and avoiding eye contact.

✓ Correct Answer: Option B

Diffident means lacking self-confidence or shy. Sarah's behavior (low voice, avoiding eye contact) indicates shyness, making 'diffident' the best fit. Garrulous means talkative; ebullient means cheerful and full of energy; gregarious means fond of company.