How are the nervous systems of a flatworm and a fish different?

A. One responds to stimuli in the environment the other does not
B. One has nerve cells with axons the other does not
C. One is a loose network of connected neurons without centers of integration and one has ganglia which integration can occur
D. One has a brain, with a forebrain, a midbrain, and a hindbrain, the other has ganglia which integration can occur