The reason for the reddish colour of red soil is

-The red soil is formed due to weathering of metamorphic and igneous rocks.
-The soil develops a reddish color due to a wide diffusion of iron in crystalline and metamorphic rocks. Hence, option 4 is correct.
-It looks yellow when it occurs in a hydrated form
-It covers about 3.5 lakh sq. km (10.6%) of the total geographical area of the country.
-Red soil is rich in potash content but lacks phosphate, humus, and nitrogen content.
-The red soil is found in regions such as Tamil Nadu, Madhya Pradesh, Jharkhand, Odisha, some parts of Karnataka and southeast Maharashtra