Final answer:
The unconscious part of personality responsible for drives like sex and aggression is the Id.
Step-by-step explanation:
The unconscious part of personality responsible for drives like sex and aggression is the Id. According to Sigmund Freud's psychoanalytic theory, the Id is the most primitive and instinctual part of our personality, operating on the pleasure principle. It is present from birth and directs our impulses for hunger, thirst, and sex. The Id seeks immediate gratification, and its drives can sometimes conflict with the demands of the superego and ego.