Scientific Attempts to Teach Apes to Speak Human Languages

Scientific attempts to teach apes to speak human languages:

A) have been extremely successful, especially with chimpanzees
B) have not been made because of the differences in the vocal tract and location of the pharynx
C) have shown that chimpanzees learn to speak Spanish easier than English
D) have been so successful with chimpanzees and gorillas that researchers are now teaching orangutans to speak
E) have made it possible for gorillas to communicate with chimpanzees