Photosynthesis is primarily considered a redox reaction. This means it involves the transfer of electrons between molecules, specifically involving oxidation and reduction processes.
During photosynthesis, light energy is harnessed to convert carbon dioxide and water into glucose and oxygen. In this process, water is oxidized (losing electrons) to produce oxygen, while carbon dioxide is reduced (gaining electrons) to form glucose. Therefore, these simultaneous oxidation and reduction reactions classify photosynthesis as a redox reaction.
In summary, the correct choice is d) redox, as this captures the essential nature of the photosynthesis process, involving both oxidation and reduction, facilitating the conversion of light energy into chemical energy.