<span>Organisms
that expend energy to regulate some or all of their internal conditions are
known as regulators. Regulators are organisms that can control their internal
environment regardless of external environmental change. Regulators achieve this
by homeostatic mechanisms and it requires a lot of energy. Examples of
regulators are mammals and birds</span>
Endocrine and circulatory (C) Endocrine system consists of glands and the hormones they secrete whist the circulatory system is the blood or as I like to call the “transport system” of the body.
The correct answer is microglia.
<span>Microglia is glial cells found in the central nervous system with the protective role. Because they are the resident macrophage cells, they act as the first and main form of active immune defense. Microglia is constantly cleaning the CNS for plaques, damaged or unnecessary neurons, and infectious agents, like viruses or other microorganisms.</span>
