Of the following choices, the best definition of aggression is __________

A) unintentionally inflicting pain on another.
B) intentionally inflicting physical or psychological harm on another.
C) intentionally inflicting psychological harm on another.
D) unconsciously inflicting physical pain on another.

Aggression involves intentionally inflicting physical or psychological harm on another. Unintentionally inflicting pain or unconsciously inflicting physical pain, while still negative behaviors, do not fit the definition of aggression as they lack the intentional aspect. Similarly, option C only involves inflicting psychological harm, while aggression can take on physical forms as well.