Which gas do plants absorb during photosynthesis?

Plants absorb carbon dioxide during photosynthesis as a key component of the process through which they convert light energy into chemical energy. In photosynthesis, chlorophyll in the plant's leaves captures light energy, which is then used to transform carbon dioxide from the air and water from the soil into glucose and oxygen. The carbon dioxide enters the leaves through small openings called stomata. This carbon is critical, as it forms the basic building blocks of the organic compounds that plants need to grow and sustain themselves.

The other gases listed do not play a direct role in the photosynthesis process in the way that carbon dioxide does. For example, oxygen is a byproduct of photosynthesis, released into the atmosphere after the conversion of carbon dioxide and water. Nitrogen is essential for the growth of plants as a nutrient, but it is not absorbed during the process of photosynthesis itself. Hydrogen is involved in the production of glucose as part of the chemical reactions during photosynthesis, but it is derived from the water molecules split during the process, not from direct absorption from the environment.