Which of the following are three major structures of the nervous system?

The three major structures of the nervous system are indeed the brain, spinal cord, and peripheral nerves. This is accurate because the brain serves as the control center for the body, processing information and coordinating responses. The spinal cord acts as the primary pathway for transmitting signals between the brain and the rest of the body, facilitating communication between the central nervous system and peripheral nervous system. Peripheral nerves are crucial as they extend from the spinal cord to the rest of the body, enabling sensory and motor functions.

The other options do not accurately represent the primary components of the nervous system. The first option lists the heart and lungs, which are part of the cardiovascular and respiratory systems, respectively. The third option includes kidneys and liver, which are organs in the urinary and digestive systems, and do not have roles in the nervous system. Lastly, the fourth option mistakenly includes veins and arteries, which are circulatory system components, rather than structures that form part of the nervous system.