Question

which diagram correctly labels the reactants and products of photosynthesis?

Explanation:

Photosynthesis uses carbon - dioxide ($CO_2$) and water ($H_2O$) as reactants, and produces glucose ($C_6H_{12}O_6$) and oxygen ($O_2$). The light - dependent reactions use light energy, $H_2O$, $ADP$, and $NADP^+$ to produce $O_2$, $ATP$, and $NADPH$. The Calvin cycle (light - independent reactions) uses $CO_2$, $ATP$, and $NADPH$ to produce $C_6H_{12}O_6$, $ADP$, and $NADP^+$.

Answer:

The diagram where $H_2O$ and $CO_2$ are labeled as reactants and $O_2$ and $C_6H_{12}O_6$ are labeled as products is correct. Without specific labels for each option, it's not possible to identify a specific lettered choice, but the correct reactant - product relationship is: Reactants are $H_2O$ and $CO_2$, products are $O_2$ and $C_6H_{12}O_6$.