What are the main components of the central nervous system?

The central nervous system (CNS) is primarily composed of the brain and spinal cord. Among the key components, the cerebrum, cerebellum, and spinal cord play critical roles in processing and transmitting information throughout the body.

The cerebrum is responsible for higher brain functions, such as thought, action, and emotion, essentially serving as the control center for sensory perception and voluntary movements. The cerebellum, located at the back of the brain, coordinates muscle movements and maintains posture and balance, ensuring smooth execution of movements. The spinal cord acts as a pathway for signals between the brain and the rest of the body, facilitating reflex actions and sensory integration.

Together, these components form the backbone of the CNS, making option A the correct answer. The other choices focus on systems or organs that do not comprise the central nervous system; thus, they are not relevant to the identification of CNS components.