Final answer:
The first theorist to focus on the unconscious mind in a clinical setting was Sigmund Freud, who established the field of psychoanalytic theory.
Step-by-step explanation:
The work of this theorist was the first to focus clinical attention on our unconscious mind: c) Sigmund Freud. Sigmund Freud, an Austrian neurologist, developed psychoanalytic theory, which emphasizes the importance of the unconscious mind in determining human behavior and personality. Freud's approach included techniques such as dream analysis and free association to explore the unconscious mind. His theories have had a significant influence on psychology and still generate interest and debate today. Freud proposed three components to our personality: the id, ego, and superego. Moreover, he suggested that personality develops through a series of psychosexual stages.