To identify the reactants of the chemical reaction, we need to consider the typical reaction in photosynthesis, which can be represented by the equation:
\[ \text{Carbon Dioxide} + \text{Water} + \text{Light} \rightarrow \text{Sugar} + \text{Oxygen} \]
In this case, the reactants are Carbon Dioxide and Water.
So the correct answer is: Carbon Dioxide and Water.