Which gas is essential for the process of photosynthesis?

Carbon dioxide is fundamental to the process of photosynthesis. During photosynthesis, plants, algae, and some bacteria convert carbon dioxide and water into glucose and oxygen, using sunlight as energy. This process takes place primarily in the chloroplasts of plant cells, where chlorophyll captures light energy.

Carbon dioxide enters the plant through tiny openings in the leaves called stomata. It is then utilized in the Calvin cycle, a series of biochemical reactions that synthesizes glucose. The glucose produced serves as a vital energy source for the plant, while oxygen is released as a byproduct, contributing to the atmosphere and supporting life on Earth.

The other gases listed, while they have important roles in different biological and ecological processes, are not directly involved in photosynthesis in the same way carbon dioxide is.