Final answer:
Freud believed that the unconscious mind is the primary influence on behavior, continuously affecting our conscious thoughts and actions.
Step-by-step explanation:
Sigmund Freud believed that a person's unconscious mind always influences behavior. Freud posited that the human psyche is comprised of the id, ego, and superego, but it is the unconscious realm of the mind that holds repressed memories and instincts which constantly influence our conscious behavior.
Freud's psychoanalytic theory asserts that the ego struggles to balance the primitive desires of the id, which operates on the pleasure principle, and the moral judgments of the superego, which develops through social interactions and demands adherence to social norms. Thus, the correct answer to the question is (b) Unconscious mind.