The correct answer is: D) H2O… CO2
Redox reactions are reactions of reduction (molecules tend to gain electrons) and oxidation (molecules tend to lose electrons).
Photosynthesis is a set of redox reactions. In photosynthesis electrons are removed from water (H2O) to carbon dioxide CO2 and then used to turn CO2 into organic compounds.
The first step: Oxygen in water is oxidized (light energy required)
The second step: Carbon in CO2 is reduced; sugar is formed (dark reaction).
