Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that is closest in meaning to each of the following questions

Mark delayed writing the book until he had done a lot of research.

A. Mark did a lot of research after he finished writing the book

B. It was only when Mark had written the book that he did a lot of research

C. Mark delayed writing the book as he had already done any research

D. Only after Mark had done a lot of research did he begin to write the book