Q: Echinoderms lack what type of system that in humans consists of the brain and spinal cord?


Read this paragraph and choose the correct option from the provided answers:

Echinoderms lack respiratory and excretory systems. Instead, the thin walls of their tube feet allow oxygen to diffuse in and wastes to diffuse out. Echinoderms also lack a centralized nervous system. They have an open circulatory system and lack a heart. On the other hand, echinoderms have a well-developed coelom and a complete digestive system. Echinoderms use pheromones to communicate with each other. They detect the chemicals with sensory cells on their body surface. Some echinoderms also have simple eyes ( ocelli ) that can sense light. Like annelids, echinoderms have the ability to regenerate a missing body part.

 Choices:

- autonomic system

- endocrine system

- peripheral nervous system

- centralized nervous system


A:
centralized nervous system