The correct answer is A. unashamed.
The word “unabashed” means “not feeling or showing shame or embarrassment.” In the context of the sentence, the speaker is describing someone who is not ashamed to give a lecture on something that is obvious to everyone. This suggests that the speaker is confident in their knowledge and abilities, and is not afraid to share their ideas with others.
The other options are incorrect because they do not accurately describe the speaker’s attitude. Option B, “unimpressed,” suggests that the speaker is not interested in what they are talking about. Option C, “unnerved,” suggests that the speaker is nervous or anxious. Option D, “unchecked,” suggests that the speaker is not being
supervised or controlled.In conclusion, the correct answer is A. unashamed.