Which statement best describes igneous rocks?

Which statement best describes igneous rocks?

• A. A category of rock formed from molten material
• B. A rock formed from sediment deposition
• C. A rock altered by heat and pressure
• D. A rock formed by chemical precipitation

Answer: (A)

Igneous rocks form from cooling and solidification of molten material. When magma erupts as lava on the surface, rapid cooling creates fine-grained or glassy rocks; when cooling happens underground, they solidify slowly into coarse-grained rocks. This molten-origin process is what sets igneous rocks apart from other types: sedimentary rocks come from sediment deposition and lithification, metamorphic rocks form when existing rocks are altered by heat and pressure, and rocks formed by chemical precipitation arise from dissolved minerals precipitating from solution. So the statement describing igneous rocks as formed from molten material is the best description.

Igneous rocks form from cooling and solidification of molten material. When magma erupts as lava on the surface, rapid cooling creates fine-grained or glassy rocks; when cooling happens underground, they solidify slowly into coarse-grained rocks. This molten-origin process is what sets igneous rocks apart from other types: sedimentary rocks come from sediment deposition and lithification, metamorphic rocks form when existing rocks are altered by heat and pressure, and rocks formed by chemical precipitation arise from dissolved minerals precipitating from solution. So the statement describing igneous rocks as formed from molten material is the best description.