The correct option is "1 and 2 only" because Cowpea and Green gram are versatile legumes that serve multiple agricultural purposes. Cowpea is commonly utilized for its edible seeds (as pulse), its leaves and stems can be used as fodder for livestock, and it also enriches soil nitrogen, making it an effective green manure. Similarly, Green gram, besides being consumed as a pulse, can also be used for fodder and contributes to soil fertility when used as green manure. In contrast, while Pigeon pea is primarily cultivated for its pulses, it is less frequently employed as fodder or green manure compared to the other two crops, which strengthens the reasoning for the selected option. This understanding is crucial for comprehending the interrelationships of crops in sustainable agriculture, aligning with UPSC’s focus on agriculture’s role in the economy and environmental management.