Question

what component of earths atmosphere exists entirely as a result of photosynthesis?
oxygen gas
water vapor
nitrogen gas
carbon dioxide gas

Explanation:

Photosynthesis is a process by which plants, algae, and some bacteria convert carbon - dioxide and water into organic compounds and oxygen using sunlight. Oxygen gas in Earth's atmosphere exists largely as a result of photosynthesis. Nitrogen gas is not a product of photosynthesis. Water vapor is part of the water cycle and not directly a product of photosynthesis in terms of being a gas component of the atmosphere due to photosynthesis. Carbon - dioxide is taken in during photosynthesis, not produced as a gas in the atmosphere as a result of it.

Answer:

D. oxygen gas