Which term relates to chemicals in the brain that regulate psychological functioning?

• A. Neurochemistry
• B. Phenotype
• C. The unconscious
• D. Ego

Answer: (A)

Neurochemistry is the study of brain chemicals and how they regulate psychological functioning. Brain chemicals, or neurotransmitters, influence mood, arousal, attention, and behavior by modulating neural communication. Because the question focuses on the chemicals in the brain that regulate psychological functioning, this term directly captures that idea, whereas phenotype is about observable traits, and the unconscious and ego come from psychoanalytic theory describing mental structures rather than chemistry. Thus, neurochemistry best matches the concept.