Task: Dialogue Generation
Input (English): F: Has your sister bought her books yet? ,M: She bought a medical book. The Chinese and English textbooks were sold out.
(A) F: Oh, she bought an English textbook,she must like English. (B) F:  she just bought a medical book? why she don't buy some Chinese and English textbooks since there are a lot of them. (C) F: Then she bought a Chinese textbook,she can study Chinese. (D) F: I am afraid I did not quite catch what you were saying. Please repeat it.
Output (English): D