Ivory from elephant tusks is a valuable commodity on the world market. As a result, male African elephants with large tusks have been heavily hunted for the past few centuries. Today, male elephants have significantly shorter tusks at full adulthood than male elephants in the early 1900s. This is an example of _________.

A. Diversifying selection;

B. Stabilizing selection;

C. Directional selection;

D. Chance;

E. More than one of the above is correct.