The correct answer is D.
To “steal someone’s thunder” means to take the attention away from someone else, especially by doing something unexpected or impressive. In this case, Deepak’s mime act detracted the listeners from Peter’s speech, which means that it took their attention away from Peter and his speech.
A. Made unimpressive: This is not the correct answer because Deepak’s mime act was actually very impressive. It was so impressive that it took the attention away from Peter’s speech.
B. Made a lot of noise: This is not the correct answer because Deepak’s mime act was not noisy. It was a silent performance.
C. Filched something: This is not the correct answer because Deepak did not steal anything. He simply performed a mime act.