Which of the following is a symbiotic nitrogen fixer?

Explanation

Azotobacter: Azotobacter is a free-living nitrogen-fixing bacterium. It forms a symbiotic relationship with some plants, especially in the rhizosphere (root zone), where it provides them with fixed nitrogen in exchange for organic carbon compounds. However, it is primarily considered a free-living nitrogen fixer.Frankia: Frankia is a genus of actinomycete bacteria that forms symbiotic relationships with certain types of plants, particularly woody plants like alders, Elaeagnus, and others. These associations are called actinorhizal symbiosis, and the plants are referred to as actinorhizal plants. Frankia helps these plants fix atmospheric nitrogen and provides them with essential nutrients.Azolla: Azolla is a water fern that can host the cyanobacterium Anabaena azollae in cavities on its upper leaf surface. This cyanobacterium is capable of nitrogen fixation and provides fixed nitrogen to the Azolla plant. This symbiotic relationship is often used in rice cultivation as a natural fertilizer.Glomus: Glomus is a genus of arbuscular mycorrhizal fungi (AMF). These fungi form mutualistic relationships with the roots of most land plants. In these relationships, the AMF assist the plant in nutrient uptake, including phosphorus, and, to some extent, nitrogen. Although they are not direct nitrogen fixers like Azotobacter or Frankia, they play a crucial role in nutrient acquisition and overall plant health.So among these, Frandia is symbiotic nitrogen fixer.