According to the work of Lieberman and Laitman,...

According to the work of Lieberman and Laitman, language as we know it
appeared about ________ years ago and is associated with the development of
the vocal tract and other capabilities of

A) 6,000 / modern civilized humans
B) 2 million / Homo habilis
C) 3 million / Neanderthals
D) 100,000 / Homo sapiens 

Additional Requirements 
Level of Detail: Only answer needed