Photosynthesis is the major source of which of the following gases in Earth's atmosphere?

• A. Methane (\(CH_4\))
• B. Nitrogen (\(N_2\))
• C. Oxygen (\(O_2\))
• D. Carbon dioxide (\(CO_2\))

Answer: (C)

Verified step by step guidance

1. Understand the process of photosynthesis: Photosynthesis is the process by which plants, algae, and some bacteria convert light energy into chemical energy stored in glucose. During this process, oxygen (\(O_2\)) is released as a byproduct.
2. Recall the chemical equation for photosynthesis: The general equation is: $\mathrm{6CO}{2}_{}+\mathrm{6H}{2}_{}O+\mathrm{light}\to C{6}_{}H{12}_{}O{6}_{}+\mathrm{6O}{2}_{}$. This shows that oxygen is produced during photosynthesis.
3. Identify the source of oxygen: The oxygen released during photosynthesis comes from the splitting of water molecules (\(H_2O\)) during the light-dependent reactions of photosynthesis.
4. Eliminate incorrect options: Methane (\(CH_4\)) and nitrogen (\(N_2\)) are not products of photosynthesis. Carbon dioxide (\(CO_2\)) is a reactant, not a product, in photosynthesis.
5. Conclude that oxygen (\(O_2\)) is the correct answer: Based on the process and the chemical equation, oxygen is the major gas released into Earth's atmosphere as a result of photosynthesis.