According to psychoanalytic theory, which of the following best applies to the development of the personality core?

a. It was developed by the age of 6 in a series of psychosexual stages.
b. It was developed after the age of 12 through social reinforcement.
c. It only developed because of unconditional positive regard from your parents.
d. Instrumental behavior was the only way it developed after the age of 6 .