Which of the Following Is True of a Child's Language

Which of the following is true of a child's language development?

A) To develop normal language, a child needs immediate reinforcement for each correct statement.
B) As early as age 2 1/2 to 3 years, children's language errors imply that they are using grammatical rules.
C) The stages of language development and the mean ages of reaching them vary greatly from one society to another.
D) Up to at least age 4, most of a child's phrases and sentences are copied directly from what they have heard other people say.