The opposable thumb is a trait that connects us to other primates; allowing us to grab and use tools and increasing chances for survival. This means it is a(n) .

The options to this question are;

A. genotype

B. adaptation

C. selective pressure

D. stabilizing pressure

The answer is B) Adaptation

Explanation:

Adaptation is the process whereby an organism becomes well suited to survive in its natural environment, which is aided by the possession of certain traits called adaptive features. For example, the fins of a fish makes it fit to survive in an aquatic environment, likewise the opposable thumbs of humans make us well suited to survive in our environment.

As stated in the question, the opposable thumb i.e. movement of the thumb independently of the other four fingers, is a characteristics of primates. This unique feature (opposable thumb) allows us to grab things, get a good grasp of tools, use tools effectively, write things, etc. All these ability due to the possession of opposable thumb increases our chances of survival. Hence, the possession of opposable thumb is regarded as an ADAPTATION

some scientists like gregory adcock agree with thorne's theory of regional continuity.

others, like chris stringer and ian tattersall, believe thorne's results may be contaminated or misinterpreted.