Explanation

The areas marked on the map are the black-soil (regur) tracts of the Deccan plateau, principally in Maharashtra and Gujarat. Black cotton soil retains moisture and is rich in calcium carbonate, magnesium and potash, making it ideally suited to cotton cultivation. This region is India's historic and leading cotton belt, which is why the marked areas account for cotton production. Groundnut dominates in Saurashtra, sugarcane in the irrigated belts of western Maharashtra and UP, and tobacco is far more localised. The official answer key gives (A) Cotton.