Despite the speaker's attempt to convey a clear message, his delivery was so _______ that many in the audience left feeling more perplexed than enlightened.

✓ Correct Answer: Option C

The sentence implies the delivery made the audience perplexed. 'Convoluted' means intricate and complicated, hindering clarity. 'Eloquent,' 'lucid,' and 'succinct' imply clarity or brevity, which contradicts the sentence's meaning.