What type of rock is formed when hot magma cools beneath the ground or lava cools above the ground?

The formation of igneous rock occurs through the solidification of magma or lava. When magma, which is found beneath the Earth's surface, cools and crystallizes, it creates intrusive igneous rocks. Conversely, when lava erupts onto the surface and subsequently cools, it forms extrusive igneous rocks. This process involves the transformation of molten rock material into solid rock, which distinguishes igneous rocks from sedimentary and metamorphic rocks.

Sedimentary rocks typically form from the accumulation and compaction of sediments, layers of minerals, and organic materials, not through the cooling of magma or lava. Metamorphic rocks arise from existing rocks that undergo changes in mineral composition and texture under pressure and heat without melting, which is a different geological process altogether. Organic rock, while not commonly classified, generally refers to sedimentary formations containing organic materials, emphasizing biological processes rather than the cooling of molten rock.

Thus, igneous rock is the correct answer because it specifically relates to the cooling and solidification of magma or lava, making it the only type of rock formed through that process.