The table shows the direction and function of substances in a chemical reaction that takes place in the chloroplasts of plant cells. The table is missing information at W, X, and Y.

In the context of the photosynthesis reaction that occurs in the chloroplasts of plant cells, substance W is most likely **d) sunlight**.

Sunlight is a crucial component of photosynthesis, as it provides the energy needed for the reaction to convert carbon dioxide and water into glucose (often stored as starch) and oxygen. Therefore, substance W would represent the light energy that drives the process.