What type of rocks are formed from the cooling of molten rock?

Igneous rocks are formed through the cooling and solidification of molten rock, which can occur either beneath the Earth's surface or after a volcanic eruption. When magma cools slowly beneath the surface, it forms intrusive igneous rocks, characterized by larger mineral crystals due to the extended cooling period. Conversely, when lava cools quickly on the Earth's surface, it results in extrusive igneous rocks, often with a finer texture since there isn't enough time for crystals to grow significantly.

The other types of rocks listed have different formation processes. Sedimentary rocks are created through the accumulation and compaction of sediment, often in layers, while metamorphic rocks result from the alteration of existing rocks under heat, pressure, or chemically active fluids without becoming molten. Volcanic rocks can often refer to those formed from lava during eruptions, which can be a subset of igneous rocks, but the more encompassing term in this context is igneous. Thus, the correct answer relates specifically to the broad category of rocks formed directly from molten materials.