The correct answer is option 2, Granite. Granite is a type of igneous rock. Igneous rocks are formed from the solidification of magma or lava. They are characterized by their crystalline structure and can have a range of textures, from fine-grained to coarse-grained.
Option 1, Limestone, is actually a sedimentary rock formed from the accumulation of calcium carbonate shells or coral fragments.
Option 3, Marble, is a metamorphic rock formed from the recrystallization of limestone.
Option 4, Slate, is also a metamorphic rock formed from the alteration of shale or mudstone.
Therefore, the only option that correctly represents an igneous rock is option 2, Granite.