Which of the following is the principal crop in areas of Extensive Commercial Grain cultivation ?

Wheat

The correct answer is Option 2: Wheat

NCERT: "Extensive Commercial Grain Cultivation Commercial grain cultivation is practised in the interior parts of semi-arid lands of the mid latitudes. Wheat is the principal crop, though other crops like corn, barley, oats and rye are also grown. The size of the farm is very large, therefore entire operations of cultivation from ploughing to harvesting are mechanised.  There is low yield per acre but high yield per person."