The correct answer is option 1: peas. Symbiotic bacteria refers to a type of bacteria that form a mutually beneficial relationship with plants. These bacteria, known as nitrogen-fixing bacteria, have the ability to convert atmospheric nitrogen into a usable form for plants. Peas, along with certain other leguminous plants such as beans and soybeans, have a symbiotic relationship with these bacteria. The bacteria live in special structures called nodules that form on the roots of these plants. Within the nodules, the bacteria convert nitrogen gas from the air into ammonia, which can be used by the plant. This process, called nitrogen fixation, helps to enrich the soil with nitrogen and improve plant growth. Therefore, peas have a particularly important role in the nitrogen cycle and in sustainable agriculture practices.