The correct answer is (d). Regur soils are formed due to weathering of basaltic lava. They are deep, black, and have a high clay content. They are well-drained and fertile, and are suitable for growing a variety of crops, including cotton, sugarcane, and rice.
Alluvial soils are formed by the deposition of sediments from rivers and streams. They are typically rich in nutrients and are well-suited for agriculture.
Laterite soils are formed in tropical and subtropical regions with high rainfall. They are typically red or yellow in color and are low in nutrients.
Red soils are formed in semi-arid regions with low rainfall. They are typically red or brown in color and are low in nutrients.