The correct answer is: a) Red and yellow soils.
Red and yellow soils are the most common type of soil found in the hilly regions of Mizoram. These soils are derived from the weathering of granite and gneiss rocks. They are characterized by their reddish-brown or yellowish color, their high content of iron oxides, and their low fertility.
Loamy soils are a mixture of sand, silt, and clay. They are generally considered to be the most fertile type of soil. However, loamy soils are not as common in the hilly regions of Mizoram as red and yellow soils.
Sandy soils are composed mostly of sand particles. They are not very fertile and do not hold water well. Sandy soils are also not very common in the hilly regions of Mizoram.
Vertisols are a type of clay soil that is found in semi-arid and tropical regions. They are characterized by their high swelling and shrinking properties. Vertisols are not common in the hilly regions of Mizoram.