When sedimentary rock is exposed to heat and pressure, what does it change into?
a. magma
c. sedimentary rock
b. igneous rock
d. metamorphic rock

The correct answer is - d. metamorphic rock.

When an already existing and fully formed sedimentary rock is exposed to higher temperatures and bigger pressures, usually deep into the ground, it slowly transforms overtime into a certain type of metamorphic rock. This occurs because the high temperature and pressure contribute to a change in the crystal structure, and also they can result into the merging of different types of rocks into one specific type of rock, which will contribute to the formation of a metamorphic rock as well.