Obsidian Is an Igneous Rock with a Glassy Appearance and Minimal

Multiple Choice

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

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