Chооse the electrоn donor, electron аcceptor, аnd cаrbon source for denitrifying bacteria from the listed options. What is the sum of their option numbers? (e.g., If sunlight is chosen as the electron donor, electron acceptor, and carbon source, then the answer is 3 (= 1+1+1). 1. Sunlight 2. Organic carbon 3. Oxygen 4. Carbon dioxide 5. Ammonia 6. Nitrate