Final answer:
Freud's genital stage marks the point where the ego and superego are fully developed with a focus on mature sexual interests.
Step-by-step explanation:
According to Sigmund Freud's psychosexual stages of development, the ego and superego are fully formed and functioning by the time a person enters the genital stage of development. This final stage, starting from puberty onwards, involves a reawakening of sexual interests where individuals redirect their incestuous urges to socially acceptable partners. Successful navigation through earlier stages without fixation leads to a well-balanced, healthy adult.