单项选择题
Choose the appropriate letter A-D and write it in box 40 on your answer sheet.
Which of the following statements best describes the writer's main purpose in Reading Passage 3? ()
A.to advise Ph.D students not to cheat while carrying out research
B.to encourage Ph.D students to work by guesswork and inspiration
C.to explain to Ph.D students the logic which the scientific research paper follows
D.to help Ph.D students by explaining different conceptions of the research process