It takes about 210 litres of water to produce 1 kg of sugar cane. Water footprint of sunflower is 7– 9 litre per kg. Millets are sown in dry areas with minimal irrigation. Red gram requires 35 to 40 cm water, during its entire growth period. Optimum moisture is required during budding, flowering, and pod formation stages. As Red gram is a rain-fed crop grown in assured rainfall areas, usually it does not need any irrigation. Hence option (a) is the correct answer.