Which nervous system description corresponds to nematodes as provided in the material?

• A. Nerve cord and ring
• B. Brain with a dorsal nerve cord
• C. Nerve net with ganglia
• D. No nervous system

Answer: (A)

Nematodes have a simple nervous system organized around a nerve ring and longitudinal cords. A nerve ring encircles the pharynx and connects to nerve cords that run along the body, providing basic coordination without a brain. This ring-and-cord layout is the best match for their nervous system description. The other options imply features nematodes don’t have—such as a brain with a dorsal nerve cord, a diffuse nerve net with ganglia, or no nervous system—so they don’t fit as well.