Igneous rock is formed by the cooling and solidification of molten Earth materials. Igneous rock forms when magma or lava cools. If igneous rock forms above ground after a volcanic eruption, it ________________ forming ____________ igneous rock, such as obsidian which is a naturally occurring volcanic glass.

Question

Responses
A cools quickly, extrusivecools quickly, extrusive
B cools quickly, intrusivecools quickly, intrusive
C cools slowly, extrusivecools slowly, extrusive
D cools slowly, intrusive

Answer 1

The correct response is: A cools quickly, extrusive.

So the complete sentence would read: "If igneous rock forms above ground after a volcanic eruption, it cools quickly, forming extrusive igneous rock, such as obsidian which is a naturally occurring volcanic glass."