The correct answer is Ego, reality principle
Ego is considered the “defender of personality” as it is responsible for preventing the unconscious contents from moving into the consciousness field, thus triggering its defense mechanisms.
Ego is guided by the principle of reality. Its main function is to satisfy the wishes of the Id as much as possible, but in a socially appropriate way. In this sense, the reality principle is opposed to the pleasure principle. But not to nullify it. Its function is to mediate the impulses of the Id so that they are satisfied according to the moral principles of social reality.