Which of the following is NOT considered a major personality structure in Freud's psychoanalytic theory?

In Freud's psychoanalytic theory, the major personality structures are the id, ego, and superego. The id represents primal desires and instincts, the ego serves as the realistic mediator between the id and the real world, and the superego embodies moral standards and ideals acquired from parents and society.

Libido, while an important concept in Freud's theory, refers specifically to psychic energy that drives individuals' sexual urges and desires. It is not classified as a distinct structure of personality like the id, ego, or superego. Instead, the libido is understood as a motivating force that influences behavior and personality development. By understanding this distinction, it becomes clear why libido does not fit into the category of major personality structures in Freud's framework.