What Evidence Do We Have That Children Who Were Not

What evidence do we have that children who were not exposed to any language at all would invent one of their own?

A) Children who were reared in orphanages in the 1930s invented a language of their own.
B) The Basque language of Spain is entirely different from that of all other European languages.
C) Deaf children who fail to learn spoken language generally invent a sign language.
D) One investigator who reared a chimpanzee with his own child found that the child and chimp communicated by their own system of grunts and whistles.