Which one of the following is NOT a metamorphic rock ?

The correct answer is (c), granite. Granite is an igneous rock, not a metamorphic rock.

Igneous rocks are formed when magma or lava cools and solidifies. Metamorphic rocks are formed when existing rocks are subjected to heat and pressure, which causes them to change their composition and texture.

Marble is a metamorphic rock that is formed when limestone is subjected to heat and pressure. Quartzite is a metamorphic rock that is formed when sandstone is subjected to heat and pressure. Schist is a metamorphic rock that is formed when shale is subjected to heat and pressure.