Which type of rock results from volcanic activity?

Igneous rocks are formed from the cooling and solidification of molten rock material, and they are categorized based on where this cooling occurs. When volcanic activity takes place, molten rock, known as magma, reaches the Earth’s surface and erupts as lava. When this lava cools quickly upon exposure to air or water, it forms extrusive igneous rock. This type of rock typically has a fine-grained texture because the rapid cooling doesn't allow large crystals to form.

In contrast, intrusive igneous rocks crystallize beneath the surface, allowing them to cool slowly and form larger crystals. Sedimentary rocks form from the accumulation of sediments, while metamorphic rocks originate from existing rocks that undergo change due to pressure, temperature, or chemically active fluids. Thus, the correct classification of the rock type resulting from volcanic activity is extrusive igneous rock, as it directly forms from the lava that erupts during a volcanic event.