TOEFL Listening: ETS-TOEFL听力机经 - 3A7IS64HYDI19G33P$

What does the professor imply when she says this? A. Some fruit flies have been trained to respond to magnetism. B. Only fruit flies that are specially bred in laboratories can sense magnetism. C. It is obvious that most laboratory fruit flies have lost some natural sensitivity. D. It is impossible to prove any connection between fruit flies and magnetism.