One of the Best Sources of Evidence That There Is

Multiple Choice

One of the best sources of evidence that there is a sensitive period for human language development is that

A) humans always develop language skills, no matter what linguistic environment they are in.
B) it can be very difficult for adults who are learning a second language to become proficient in the grammar of that language.
C) it is nearly impossible for children to master two languages before the age of ten.
D) the later one starts learning a language, the better he or she is at mastering the phonemes in the new language.