The correct option is
D All of the above
Crotalaria juncea, known as sunn or sunn hemp, is a tropical Asian plant of the legume family (Fabaceae). It is generally considered to have originated in India. It is now widely grown throughout the tropics and subtropics as a source of green manure, fodder and lignified fiber obtained from its stem. Sunn hemp is also being looked at as a possible bio-fuel. It is most commonly used as green manure in India.
Vigna sinensis or cowpea is one of the most widely used legumes in the tropical world. The grain is used widely for human nutrition, especially in Africa. It is one of the most important tropical dual-purpose legumes, being used for vegetables (leaves and flowers), grain, as fresh cut and carry forage, and for hay and silage. The species has a high potential as a green manure. It can be incorporated into the soil or spread on the soil surface 8-10 weeks after sowing and can provide the equivalent of 80 kg/ha N to a subsequent crop.
Berseem is a nitrogen-fixing legume. It may require Rhizobium inoculation outside its native area. As a winter crop, it provides soil cover and prevents erosion.
So, the correct answer is option D.