Igneous rocks are classified based upon their
a. mineralogy and composition
b. crystal texture and density
c. crystal size and mineral composition
d. hardness and texture

The answer should be C, Crystal size and mineral composition

Explanation:

I did this question on edg2020, plus it's the only one that makes sense.

Here are notes:

Crystal size and texture are determined by how a rock forms

Intrusive rocks have alrger crystals and a coarse texture

Extrusive rock have small crystals and a fine texture