Which of Plato's Beliefs Established the Concept of Dualism

Which of Plato's beliefs established the concept of dualism?

A) Human beings have immortal souls that are separate and distinct from their physical bodies.
B) Forms exist as invisible and abstract ideals of reality, but humans perceive only flawed and vague dual images of these Forms.
C) Ethical qualities, such as goodness, do not exist as absolutes in our world, and their earthly forms can show an opposite quality, such as evil.
D) Because moral values are actually absolutes, the human experience of these values creates a dual value system.