Sentence A starts the paragraph by stating the topic of discussion (Why did the Chinese central bank cut interest rates again?). It may seem that sentence D should follow this as it has the term 'answer'. However, sentence B should follow A as it has the term 'ask this' and hence is a continuation to sentence A. Sentence C has the term 'same week' which is the week of October 23 rd. So, A-B-C follow each other. This is followed by sentence D which finally states the answer to the question posed by sentence A.
So, the answer is ABCD.