Final answer:
Sigmund Freud would most likely attribute aggressive behavior to unresolved conflicts and drives at the unconscious level, reflecting a struggle among the id, ego, and superego.
Step-by-step explanation:
According to Sigmund Freud, the most likely explanation for why someone is behaving aggressively is that there is something going on at the unconscious level that is causing them to behave this way. Freud's theory of personality suggests that our behavior is influenced by the unconscious drives motivated by sex and aggression, as well as the interactions between the id, ego, and superego. The id is seeking to satisfy basic urges, the superego aims to uphold moral standards, and the ego moderates between the demands of the id, the superego, and reality. It's the ego's job to balance these impulses with the reality principle. When there is an imbalance or unresolved conflict, it may manifest as aggressive behavior.