The right option is; igneous rocks are always thin and brittle
Igneous rocks are rocks that are formed when hot magma or lava cools and solidifies to form crystal structured rocks. Igneous rocks are not always thin and brittle. Igneous rocks differ in their textures, colors, and mineral composition. Igneous rocks are of two groups which are intrusive rocks; those that solidifies into rocks below the earth surface and (ii) extrusive rocks; those that solidifies into rocks on the earth surface.