Which statement accurately describes the rock cycle and the formation of igneous, sedimentary, and metamorphic rocks?

• A. Igneous rocks form from weathering and deposition.
• B. Sedimentary rocks form by cooling of magma.
• C. Igneous form from cooling magma/lava; sedimentary form from lithified sediments; metamorphic form from existing rocks altered by heat/pressure.
• D. Metamorphic rocks form only from biological processes.

Answer: (C)

The rock cycle describes how rocks form and transform through cooling, lithification, and metamorphism. Igneous rocks come from molten rock that cools and solidifies, whether underground as magma or on the surface as lava. Sedimentary rocks form from sediments produced by weathering and erosion, which are deposited and then lithified through compaction and cementation. Metamorphic rocks arise when existing rocks are altered by heat, pressure, and chemically active fluids, causing minerals to recrystallize without melting. This set of processes matches how the three rock types are created and connected in the cycle. The other statements mix up these processes—for example, igneous rocks don’t form from weathering and deposition, sedimentary rocks don’t form by cooling of magma, and metamorphism isn’t biological.