Which statement best describes the formation of metamorphic rocks? Magma cools and crystallizes slowly beneath Earth’s surface.
Liquid lava erupts from a volcano and cools quickly at Earth’s surface.
Sand and gravel are deposited at the mouth of a river and, over time, form layers that solidify into rock.
Ancient sandstone beaches become buried deep beneath Earth’s surface, where they are exposed to extreme heat and pressure.

Ancient sandstone beaches become buried deep beneath Earth’s surface, where they are exposed to extreme heat and pressure is the correct answer.

Explanation:

Metamorphic rocks are formed when the preexisting rocks are subjected to high pressure and heat in a method called metamorphism,Metamorphic rocks may be created by being buried below the Earth's surface,when subjected to high heat and high pressure.Metamorphic rocks are derived from igneous or sedimentary rocks. Examples of metamorphic rocks are schist, quartzite, marble, slate, gneiss, and anthracite.Thus Ancient sandstone beaches become buried deep beneath Earth’s surface, where they are exposed to extreme heat and pressure best describes the formation of metamorphic rocks.