【单选题】

Sign has become a scientific hot button. Only in the past 20 years have specialists in language study realized that signed languages are unique -- a speech of the hanD、They offer a new way to probe how the brain generates and understands language, and throw new light on an old scientific controversy: whether language, complete with grammar, is something that we are born with, or whether it is a learned behavior. The current interest in sign language has roots in the pioneering work of one rebel teacher at Gallaudet University in Washington,D、C、, the world’’s only liberal arts university for deaf people.WhenBill Stokoe went to Gallaudet to teachEnglish, the school enrolled him in a course in signing.But Stokoe noticed something odd: among themselves, students signed differently from his classroom teacher.Stokoe had been taught a sort of gestural code, each movement of the hands representing a word inEnglish.At the time,American Sign LanguageASL) was thought to be no more than a form of pidginEnglish (混杂英语).But Stokoe believed the "hand talk" his students used looked richer. He wondered: Might deaf people actually have a genuine languageAnd could that language be unlike any other onEarth It was 1955, when even deaf people dismissed their signing as "substandard". Stokoe’’s idea was academic heresy (异端邪说).It is 37 years later. Stokoe -- now devoting his time to writing and editing books and journals and to producing video materials onASL and the deaf culture -- is having lunch at a caf6 near the Gallaudet campus and explaining how he started a revolution. For decades educators fought his idea that signed languages are natural languages likeEnglish, French and Japanese. They assumed language must be based on speech, the modulation (调节) of sounD、But sign language is based on the movement of hands, the modulation of space. "What I said," Stokoe explains, "is that language is not mouth stuff -- it’’s brain stuff." Stokoe’’s argument is based on his belief that ________.

A、sign language is as efficient as any other language
B．sign language is derived from natural language
C．language is a system of meaningful codes
D．language is a product of the brain