Which of the following is a reducing agent in the overall reaction for photosynthesis?

• A. Water ($H_{2}O$)
• B. Oxygen ($O_2$)
• C. Glucose ($C_6{H}_{12}{O}_6$)
• D. Carbon dioxide (${\mathrm{CO}}_2$)

Answer: (A)

Verified step by step guidance

1. Understand the concept of a reducing agent: A reducing agent is a substance that donates electrons to another substance, reducing it in the process.
2. Identify the overall reaction for photosynthesis: The general equation for photosynthesis is 6CO2 + 6H2O + light energy → C6H12O6 + 6O2.
3. Analyze the role of each reactant and product: In the photosynthesis equation, water (H2O) is oxidized to oxygen (O2), meaning it loses electrons.
4. Determine which substance donates electrons: Since water (H2O) loses electrons to form oxygen (O2), it acts as the reducing agent in the reaction.
5. Conclude that water (H2O) is the reducing agent in the overall reaction for photosynthesis, as it donates electrons during the process.