The correct answer is option 4, Gneiss.

First, let`s understand what igneous rocks are. Igneous rocks are formed from the solidification of molten material, either magma (molten rock below the surface) or lava (molten rock on the surface). These rocks are classified based on their texture and composition.

Now let`s analyze each option to see if it qualifies as an igneous rock:

- Option 1: Granite is indeed an igneous rock. It is a coarse-grained rock formed from the slow cooling and solidification of magma underground.

- Option 2: Basalt is also an igneous rock. It is a fine-grained rock formed from the rapid cooling and solidification of lava on the Earth`s surface.

- Option 3: Gabbro is another igneous rock. It is a coarse-grained rock formed from the slow cooling and solidification of magma underground, similar to granite.

- Option 4: Gneiss is not an igneous rock. It is a metamorphic rock formed from the transformation of existing rocks due to intense heat and pressure. Gneiss has a banded texture and typically forms from rocks like granite or shale.

In conclusion, option 4, Gne