The correct answer is (d), Pongam.
Pongam is a leguminous plant that is also a petro-plant. This means that it can be used to produce biodiesel, a type of renewable fuel that is made from vegetable oils. Pongam oil is a good source of biodiesel because it is high in energy and has a low sulfur content. It is also non-toxic and biodegradable, making it a safe and environmentally friendly fuel.
Pigeon-pea, pea, and gram are all leguminous plants, but they are not petro-plants. Pigeon-pea is a type of pea that is grown in tropical and subtropical regions. It is a major source of protein and carbohydrates for people in many parts of the world. Pea is a type of legume that is grown in temperate regions. It is a major source of protein and carbohydrates for people in many parts of the world. Gram is a type of legume that is grown in tropical and subtropical regions. It is a major source of protein and carbohydrates for people in many parts of the world.
Pigeon-pea, pea, and gram are all important crops, but they do not have the same potential as pongam for producing biodiesel. Pongam is a more efficient source of biodiesel, and it is also a more environmentally friendly fuel.