Simon showed grammatical mastery for the rules of American Sign Language, even though his teachers (his parents and their friends) did not. This lends support for the idea that

A) there is no sensitive period for learning language.
B) ASL cannot be taught to children after the age of 9.
C) the tendency to acquire language is inborn.
D) a child can learn grammatically incorrect ASL, even if the parents model correct usage.

American Sign Language

A complete, natural language that has the same linguistic properties as spoken languages, utilized by the deaf community in the United States and parts of Canada.

Grammatical Mastery

The high level of skill or proficiency in understanding and using the rules of a language's syntax and structure.

Sensitive Period

A time frame in development when the organism is more responsive to certain stimuli or experiences, leading to the formation of specific abilities.