The answer is C I just wanted to answer it for you Let me explain why Food provides glucose. This is because glucose is a type of sugar that we gain from the food we eat. It is also one of the two reactants in the cellular respiration equation. The two are glucose and oxygen. Therefore glucose would be the the answer because it is a reactant of the equations and therefore a part of cellular respiration.

Which explains why it is important to eat a full healthy meal before an afternoon of playing sports?

Food provides the carbon dioxide that is a product of cellular respiration.

Food provides the oxygen that is a product of cellular respiration.

Food provides the glucose that is a reactant in cellular respiration.

Food provides the energy that is a reactant in cellular respiration.