D. Rarely does Kate visit the gym.
Feedback When we want to speak in a more formal and literary way or we want to emphasize some idea in the sentence, we use the inversion. In this case the speaker wanted to point out the adverb 'rarely'. We put it in the first place. We place the auxiliary verb after the adverb 'rarely'. So the word order is: [adverb — auxiliary — subject — verb — object]