Explanation:

During photosynthesis, plants use sunlight to convert water (H₂O) and carbon dioxide (CO₂) into glucose (C₆H₁₂O₆) and oxygen (O₂).

The oxygen (O₂) released as a byproduct comes from water molecules, not from carbon dioxide. This process occurs in the light-dependent reactions of photosynthesis, specifically during photolysis, where water molecules are split by sunlight.