What are the main components of the nervous system?

The correct answer identifies the brain, spinal cord, and nerves as the main components of the nervous system. The nervous system is essential for controlling and coordinating bodily functions, processing sensory information, and facilitating communication between different body parts. The brain serves as the control center for processing information and making decisions, while the spinal cord acts as a conduit for signals traveling between the brain and the rest of the body. Nerves extend from the spinal cord to various parts of the body, transmitting signals that enable responses to stimuli.

In contrast, the other choices represent systems or organs not related to the nervous system. The heart, blood vessels, and lungs are components of the circulatory and respiratory systems, which are critical for transporting oxygen and nutrients throughout the body. The kidneys, liver, and pancreas are part of the excretory and digestive systems, involved in metabolic processes and waste elimination. Lastly, muscles, tendons, and ligaments belong to the musculoskeletal system, which is responsible for movement and structural support. Understanding these distinctions highlights the unique role that the brain, spinal cord, and nerves play specifically within the nervous system.