The correct answer is: D. Both are correct and R is the correct explanation of A.
Red and yellow soils are found in the South plateau region because of the presence of iron oxide. Iron oxide is a mineral that gives soil its red or yellow color. It is also a major component of many types of rocks, including sandstone and granite. When these rocks are weathered, the iron oxide is released and forms a layer of soil. This soil is rich in nutrients and is ideal for growing crops.
The reason (R) is the correct explanation of the assertion (A). The presence of iron oxide gives red and yellow soils their characteristic color.