A simple nervous systemA simple nervous systemincludes sensory information but no effectors. has information flow in only one direction: toward an integrating center. has information flow in only one direction: away from an integrating center. must include chemical senses and vision. includes sensory information, an integrating center, and effectors.

includes sensory information, an integrating center, and effectors

Explanation:

The basic structure of any nervous system contains the sensory part, an integrating center and the effector part. Sensory information is brought to the integrating center where it is processed and the effectors are made to respond accordingly.

Even the simplest nervous system present in cnidarians has this system where sensory ganglia plays the role of integrating center and processes the incoming information. With evolution, simple nervous systems also evolved to perform more complex tasks like processing vision or odor.