TOEFL Listening: ETS-TOEFL听力机经 - RFSRCG13CYDK1234P$

What does the professor imply about the nest-collection method? A. It does not provide all the information that traditional methods do. B. It is less expensive than other hair-collection methods. C. It is essentially too invasive to be useful to researchers. D. It is most accurate when used in areas isolated from humans.