Answer:
Igneous rocks form when molten rock (magma or lava) cools and solidifies. Sedimentary rocks originate when particles settle out of water or air, or by precipitation of minerals from water. Crystallization, erosion, sedimentation, and metamorphism transform one rock type into another or change sediments into rock. The rock cycle describes the transformations of one type of rock to another. The process by which a rock changes form or mineral content as a result of environmental changes such as heat and pressure. a rock that was altered by metamorphism.
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>
