Which type of rock is formed from the solidification of magma?

Igneous rock is formed through the solidification of magma, which is molten rock found beneath the Earth's surface. When magma cools and crystallizes, it can form intrusive igneous rock, such as granite, if it solidifies slowly beneath the surface, or extrusive igneous rock, such as basalt, if it erupts onto the surface and cools more quickly. The process of solidification involves the cooling of magma and the subsequent crystallization of minerals, which is a defining characteristic of igneous rocks.

Metamorphic rock, in contrast, originates from existing rocks that have undergone significant changes due to heat, pressure, or chemically active fluids, rather than from the solidification of magma. Sedimentary rock forms from the accumulation and lithification of sediment, often including fragments of other rocks, minerals, or organic materials, which is quite different from the formation process of igneous rocks. Composite rock is not a standard classification in geology and might refer to various mixtures of rock types, but it does not specifically describe the process of magma solidification. Hence, igneous rock is the only correct classification related to the solidification of magma.