The Example of Extended Lactose Tolerance in Humans Tell Us

The example of extended lactose tolerance in humans tell us that

A) it is entirely under genetic control, and researchers agree that the environment plays no role in its development.
B) it is one of many aspects of human biology governed by both genes and by phenotypical adaptation to environmental conditions.
C) the production of the enzyme lactase and the ability to tolerate milk remain the same among all human populations.
D) studies indicate that people cannot increase their lactose tolerance, thereby discounting the theory of phenotypical adaptation.
E) a simple genetic trait accounts for the ability to digest milk.