Obsidian Is an Igenous Rock with a Glassy Appearance and Minimal

Multiple Choice

Obsidian is an igenous rock with a glassy appearance and minimal crystal growth. What accounts for this?

A) Obsidian is an intrusive igneous rock that cooled slowly beneath the Earth's surface, result in little crystal growth.
B) Obsidian is an extrusive igneous rock that cooled slowly on the Earth surface, resulting in little crystal growth.
C) Obsidian is an extrusive igneous rock that cooled very slowly on the Earth surface, resulting in little crystal growth.
D) Obsidian is an intrusive igneous rock that cooled rapidly beneath the Earth's surface, result in little crystal growth.