When heat and pressure are applied to rocks to the point that their texture and mineralogy change, they are known as metamorphic rocks (D). For instance, limestone (a sedimentary rock) when exposed to tremendous heat and pressure is metamorphosed into marble.

Igneous (A) rocks are composed of solidified lava or magma.

A precipitate (B)(a substance, usually crystalline, separated out from a solution as a solid) can help in the formation of sedimentary (C) rocks. Sedimentary rocks can form as well from consolidated weathered rock fragments.