The nervous system is a highly complex system of nerve cells and fibers that transmits nerve impulses between parts of the body and helps maintain balance within organ systems.

• A. A network of hormones controlling growth
• B. The nervous system is a highly complex system of nerve cells and fibers that transmits nerve impulses between parts of the body and helps maintain balance within organ systems.
• C. A muscle group that coordinates movement
• D. The respiratory network in the lungs

Answer: (B)

Think of the nervous system as the body's communication and control network. It uses nerve cells and fibers to send electrical impulses rapidly between the brain, spinal cord, and all parts of the body, coordinating actions and helping maintain balance (homeostasis) across organ systems. The statement precisely captures this role by describing the complex network and its function in transmitting impulses and keeping systems in balance. The other options point to different systems—the endocrine system (hormones), the muscular system (muscle groups), and the respiratory system (lungs)—so they don’t describe the nervous system.