Silica is a chemical compound
a. that combines carbon and sand to create glass.
b. most commonly found in sand or quartz.
c. which permits light to pass through.
d. colored using metallic salts.

The correct answer is b. most commonly found in sand or quartz.

It can also be found in various living organisms, but sand and quartz are the main places where Silica can be found. Silica is actually Silicon dioxide, a compound.