What component of Earth's atmosphere exists entirely as a result of photosynthesis?

oxygen gas
water vapor
nitrogen gas
carbon dioxide gas

Oxygen gas

Explanation:

Photosynthesis is where carbon dioxide, water, and sunlight are turned into oxygen, and glucose (energy for the plant). The only gas released is oxygen.

sodium i think the chemical element of atomic number 11, a soft silver-white reactive metal of the alkali metal group.

answer: ice crystals in air

the water from the water body or another source of water gets evaporated as water vapor as an effect of heat on water. these water vapor rises in the upper layers of the earth atmosphere under high atmospheric pressure. the atmospheric pressure of these water molecules starts to decrease due to the effect of cold air. the invisible water vapor condenses into visible water droplets and ice crystals.these ice crystals and water droplets being less denser than the surrounding air floats on air as clouds.