Why Did American Sign Language Receive a Great Attention in Language

Multiple Choice

Why did American Sign Language receive a great attention in language research?

A) Because of its particular structural complexity that makes it different from the other sign languages.
B) Because it's the only sign language that uses body postures instead of finger, hand, and arm configurations.
C) Because of attempts to teach it to great apes.
D) Because it only uses finger configurations, maintaining hands and arms in fixed positions.