Gneiss, found in the Teton Range, is what type of rock?

Gneiss, found in the Teton Range, is what type of rock?

A Metamorphic
B Igneous
C Sedimentary

Metamorphic rocks are formed when existing rock is subject to heat, pressure, or chemically active fluids over long periods of time. Much of the Teton Range is made up of gneiss estimated to be about 2.7 billion years old, which formed when two tectonic plates collided.

The correct answer is Metamorphic.