Answer: The correct answer is X represents water and Z represents oxygen.
Explanation:
Cellular respiration is defined as the breaking of sugar into a form that a cell can use as energy. This breaking of glucose takes place in the presence of oxygen gas.
Equation for the cellular respiration is given by the chemical reaction:

Here,
= Glucose
For the given chemical equation in the question,

Z represents oxygen gas
X represents either carbon dioxide or water
Y represents either carbon dioxide or water
Hence, the correct answer is X represents water and Z represents oxygen.