She used to disparage her neighbour every now and then.

The correct answer is A. denigrate.

To denigrate means to speak about someone or something in a very negative way. It is a form of criticism that is often unfair or unjustified.

The other options are not as accurate as denigrate.

To belittle means to make someone or something seem less important or valuable than they really are.

To praise means to express admiration or approval of someone or something.

To please means to make someone happy or satisfied.

In the given sentence, the speaker is saying that she used to speak about her neighbor in a very negative way. This suggests that the speaker was denigrating her neighbor.