Known for his _____, the professor often digressed during lectures, weaving in anecdotes and personal reflections that, while entertaining, sometimes obscured the main topic.

✓ Correct Answer: Option C

The description of the professor 'digressing' and 'weaving in anecdotes' points to excessive talkativeness. 'Volubility' means the quality of talking fluently, readily, or incessantly, which fits perfectly.