Ninety-five percent of igneous rocks and metamorphic rocks are below
Earth's surface. Why is this true?

This is so cause ...

Igneous rocks are formed when the  molten material cools and hardens

and

Metamorphic rocks  form when they are subjected to high temperatures and the great pressure of the rock layers above it.

So most of these rocks are found beneath the earth''s crust

(I hope im right... this might not be the perfect answer... but this as close as I can get.. I hope it usefull  for u )

i had this on my unit activity, i can you if you are a plato student. are you a plato student?