According to Stokoe, sign language is ______.

A．a new way to look at the lemming of language
B．a challenge to traditional views on the nature of language
C．an approach to simplify the grammatical structure of a language
D．an attempt to clarify misunderstanding about the origin of language

A．sign language was not extensively used even by deaf people
B．sign language was too artificial to be widely accepted
C．a language should be easy to use and understand
D．a language could only exist in the form of speech sounds