What gas do plants absorb from the atmosphere?

Plants absorb carbon dioxide from the atmosphere for the process of photosynthesis. During this process, they take in carbon dioxide through tiny openings in their leaves called stomata. This gas, along with water and sunlight, is converted into glucose, a type of sugar that serves as energy for the plant, and oxygen, which is released back into the atmosphere as a by-product.

The other gases mentioned do play roles in the environment, but they do not directly contribute to the photosynthetic process in plants. While oxygen is produced by plants during photosynthesis, they do not absorb it; instead, they absorb carbon dioxide to synthesize food. Nitrogen is vital for plant growth and is absorbed by plants primarily in the form of nitrates from the soil, not directly from the atmospheric gas. Hydrogen, while part of water, is not a gas that plants absorb directly from the atmosphere either. Thus, the correct answer highlights the essential role of carbon dioxide in plant life and the fundamental process of photosynthesis.