The fact that human aggression varies widely from culture to culture most strongly suggests that it is NOT

A) a reaction to frustration.
B) influenced by social norms.
C) an unlearned instinct.
D) a product of deindividuation.

The wide variation of human aggression across different cultures suggests that it is not solely an unlearned instinct, as instincts would be more uniform across humanity. Instead, this variation implies that aggression is significantly influenced by cultural, social, and environmental factors.