In photosynthesis, plants convert carbon dioxide (CO2) and water (H2O) into glucose (C6H12O6) and oxygen (O2) using sunlight. If the diagram summarizes the inputs and outputs of photosynthesis, and substance Y is one of the reactants, it is likely to be either carbon dioxide or water.
However, without seeing the diagram, I can't definitively tell which substance Y is. Given the typical context of photosynthesis, though, if Y is one of the reactants, the answer could be:
- If Y is the substance produced, then it would be glucose (answer a) or oxygen (answer b).
If you can provide more context, I can help clarify further.