The West Coast of the United States Has Many Volcanoes

Short Answer

The West Coast of the United States has many volcanoes and earthquakes.What is a logical conclusion about the geology of this area
a)The area is composed mainly of sedimentary rocks.
b)The area is composed mainly of metamorphic rocks.
c)The area is located close to tectonic activity.
d)The area used to be a shallow inland sea.