When a population is split into smaller groups, why do these groups develop different traits?
A. Evolutionary mechanisms work the two subgroups
independently
B. Separating the two groups decreases the chance that the two
groups will diverge.
C. Gene flow is increased in the two subgroups that are formed.
D. Traits that form in one group from evolutionary forces quickly
spread through both populations.

A. Evolutionary mechanisms work the two subgroups  independently.

Explanation:

Speciation can be defined as the process by which new species develop from the pre-existing species. It occurs when the members of the same species get separated. The separated members become reproductively isolated and diverge.

The speciation of two separated members will take place individually due to the development of new traits according to the need of new habitat and other survival conditions. Thus evolutionary mechanism will work independently for  the two subgroups.

digestion

it excretes wastes