Step 1: Understanding regur.
Regur is another name for black soil, which is very fertile and suitable for growing cotton. It is found mainly in Maharashtra, Madhya Pradesh, and parts of Gujarat.
Step 2: Analyzing the options.
(A) Red soil: Incorrect, formed due to iron oxide content.
(B) Black soil: Correct — regur is black soil.
(C) Alluvial soil: Found in river basins, not regur.
(D) Laterite soil: Found in high rainfall areas, not regur.
Step 3: Conclusion.
The correct answer is (B) Black soil, which is also called regur.