Which rock type is formed through sedimentation?

Sedimentary rock is formed through the process of sedimentation, which involves the accumulation and compaction of sediments. These sediments can be derived from the weathering and erosion of pre-existing rocks, organic materials, or chemical precipitation. Over time, layers of sediment accumulate in various environments, such as rivers, lakes, and oceans. The weight of these accumulating layers compacts the deeper layers, and minerals precipitate from water, binding the sediments together to form solid rock.

This process distinguishes sedimentary rock from the other types mentioned. Metamorphic rocks form when existing rocks undergo significant heat and pressure, altering their mineral composition and structure without melting. Igneous rocks are formed from the cooling and solidification of molten material (magma or lava). Volcanic rock is another term often used to describe igneous rock that forms from lava that cools quickly on the Earth's surface. Therefore, the characteristics and formation processes of sedimentary rock highlight why it is the correct answer in relation to sedimentation.