Which one of the following rocks is an example of sedimentary rock?

Rocks are grouped into three classes based on how they form: igneous rocks crystallize as molten magma or lava cools and solidifies; sedimentary rocks form when loose particles such as mud, clay, sand, or organic debris settle in layers and are then compacted and cemented together over long periods; and metamorphic rocks form when an existing rock is transformed by heat and pressure, without melting, often developing a foliated or banded texture.

• Shale is built from fine clay and mud particles that settled in layers and were later compacted and cemented -- exactly the process that defines a sedimentary rock, which is why it is the correct choice here.

• Marble results from limestone recrystallizing under intense underground heat and pressure, so it belongs to the metamorphic class rather than the sedimentary one.

• Granite crystallizes as magma cools slowly deep below the surface, a solidification-from-melt process that makes it an igneous rock.

• Slate forms when the clay minerals in shale or mudstone realign under pressure into thin parallel layers, a pressure-driven transformation that places it among the metamorphic rocks.

Cross-check: of the four options, only Shale shows fine, layered bedding built from deposited sediment grains -- the defining signature of a sedimentary rock -- while Marble, Granite, and Slate each show a different formation process (recrystallization, cooling from melt, and foliation respectively), confirming Shale as the correct answer.