What Key Feature of Chimpanzee Tool Use Have Anthropologists Identified

What key feature of chimpanzee tool use have anthropologists identified?

A) Although chimpanzees are intelligent, their ability to use tools is so advanced that it is assumed that a large part of that ability is genetic.
B) Chimpanzees, being very intelligent, learn to modify and use tools in the wild, but active teaching of the young by adults seems to be only found in humans; chimpanzees do not do this.
C) Even though chimpanzees independently learn to use tools across Africa, the exact kind of tool and its use almost never varies from place to place; all chimpanzee groups have the same three or four tools.
D) Chimpanzees are highly intelligent; mothers have been seen teaching their young to use tools; which tools are used and for what purposes varies from location to location.