Which factor would affect photosynthesis the least? amount of carbon dioxide in the air nitrates in the soil amount of light availability of water in the soil?

The factor that would least affect photosynthesis is Nitrates in the soil.
Photosynthesis is the process by which plant make their own food by utilizing energy from sunlight, water and carbon dioxide. The limiting factors that affect photosynthesis are the light intensity, carbon dioxide concentration, temperature and water. Without enough light, a plant cannot photosynthesize very quickly, even if there is plenty of water and carbon dioxide.