Explanation:
sorry, I may use old terms; I believe it is at the hypothalamus, for endocrine system...
I think it is keystone. If they were not there the population of urchins would go up and the kelp would go down.
The first one, Added removed or changed. Mutation as in anything that would cause the slightest change.
The neuron, or nerve cell, is the basic functional unit of the nervous system
The question is B because the water move from the land to the air
