The Pygmies of Central Africa and the Arapesh of New Guinea live in peace and harmony. Formerly peace-loving, the Iroquois became a fierce and aggressive Native American tribe in the seventeenth century. These examples illustrate that

A) humans will always eventually exhibit aggressive tendencies.
B) in humans, innate behavioural patterns, including aggression, are infinitely malleable and modifiable.
C) there are strong regional differences in the endorsement of aggression as a solution to social problems.
D) humans, lacking inhibitory mechanisms, must rely on cultural norms to curb aggression.
E) frustration often contributes to aggression in otherwise peaceable societies.

B) in humans, innate behavioural patterns, including aggression, are infinitely malleable and modifiable.