Answer:
D. igneous
Explanation:
The rocks formed by cooling down of lava are called as igneous rocks. They are of two types. Intrusive igneous rocks are formed when the magma cools down inside the Earth. Extrusive igneous rocks are formed when the magma is exploded out of volcano in form of lava. Lava cools down on the surface of earth and forms extrusive igneous rocks.
