The American Quakers and Amish, Who Live in This Country's

The American Quakers and Amish, who live in this country's increasingly violent culture, exhibit nonviolence as a way of life, which shows that

A) biological factors have no effect on one's tendency toward aggression.
B) these groups of people inherited docile temperaments.
C) these groups of people have adopted a state of learned helplessness.
D) humans are capable of learning to inhibit aggression.