Igneous rocks are rocks that solidify from molten or partially molten material. Igneous rocks formed within the crust are called plutonic rocks or intrusive rocks. Plutonic rocks form when magma solidifies slowly below the Earth's surface, resulting in a coarse-grained texture. In contrast, volcanic rocks or extrusive rocks form when magma or lava solidifies quickly on the Earth's surface, resulting in a fine-grained texture. Therefore, the correct answer to the question is plutonic.