TOEFL Listening: ETS-TOEFL听力机经 - 31B3331E1K3J4N93P$

What does the professor imply when she says this? A. She's not sure the man should write about bird migration. B. She thinks finding sources on bird migration should be easy C. She's not sure that she can help the man. D. She thinks that man has already found enough sources on bird migration.