Instead of spending the weekend working on the research paper due at the end of next week, Andrew decided to spend the weekend going out with friends. According to Freudian theory, which system dominated in Adam's decision

The answer is the Id.

Explanation:

According to Freud, human personality is essentially divided in three systems of structures: The Id, the Ego and the Superego. The Id is the only structure present from birth. It is driven by instinct and the pleasure principle. In infants, for example, it is responsible for the feelings of thirst and hunger. However, the Id only seeks for immediate satisfaction. For this reason, the Ego must regulate these impulses and turn them into more realistic alternatives.