The answer would be letter A. globular cluster. This group of very old stars that are clustered together in a spherical in shape and can contain from 10,000 to several million is called a globular cluster. In our galaxy, there are 150 globular clusters.
I found the attached image on the internet related to this question.
The solid arrows represent neuronal communication. The stimulus, the effects, and the flow of information is all done by receptors and synapses that send a signals across the body in order to have effective feedback responses promoting the homeostasis of the organism.
Vertraes have a back bone. invertebrates dont have a back bone or any bones