What Is Meant by the Notion of a Critical Period

Multiple Choice

What is meant by the notion of a critical period for language acquisition

A) It is the time in one's childhood in which language must develop if it is to be fully learned.
B) It is the period of transition between one-word and two-word utterances.
C) It is the period between 2 and 5 years of age, in which vocabulary growth is especially rapid.
D) It is the period isolated children spend by themselves before someone teaches them language.