Which of the following are nitrogen-fixing plants? 1. Alfalfa 2. Amaranth 3. Chickpea 4. Clover 5. Purslane (Kulfa) 6. Spinach Select the correct answer using the code given below:

Nitrogen-fixing plants are those that can convert atmospheric nitrogen (N2) into ammonia (NH3) through a symbiotic relationship with nitrogen-fixing bacteria, primarily Rhizobium bacteria living in root nodules. These are typically legumes. Let's examine the given plants: 1. **Alfalfa:** Correct. Alfalfa (Medicago sativa) is a leguminous forage crop widely known for its ability to fix atmospheric nitrogen, significantly improving soil fertility. 2. **Amaranth:** Incorrect. Amaranth (Amaranthus spp.) is a leafy vegetable and grain crop. It is not a legume and does not fix nitrogen. It is known for being a high-nitrogen feeder. 3. **Chickpea:** Correct. Chickpea (Cicer arietinum) is a well-known legume and a pulse crop. Like other legumes, it forms a symbiotic relationship with nitrogen-fixing bacteria in its root nodules. 4. **Clover:** Correct. Clover (Trifolium spp.) is a common leguminous cover crop and forage plant widely used in agriculture for its nitrogen-fixing capabilities and soil improvement benefits. 5. **Purslane (Kulfa):** Incorrect. Purslane (Portulaca oleracea) is a succulent leafy vegetable. It is not a legume and does not fix nitrogen. 6. **Spinach:** Incorrect. Spinach (Spinacia oleracea) is a leafy green vegetable. It is not a legume and is known for being a heavy feeder of nitrogen from the soil, rather than fixing it. Therefore, Alfalfa, Chickpea, and Clover are nitrogen-fixing plants.