40. What is language acquisition device? (A) It is a metaphorical term that linguists use to describe how children learn the grammatical rules of a language through explicit instruction from adults. (B) It is one form of cognition to analyze grammatical rules that children are taught formally in school. (C) It is a symbolic term Chomsky uses to describe how children develop new verbal habits. (D) It is a hypothetical tool in the brain that helps children acquire a language.