What effect does a limiting reagent have in a chemical reaction?

In a chemical reaction, the limiting reagent is the reactant that is completely consumed first, thereby restricting the amount of product that can be formed. This means that the limiting reagent effectively sets a limit on the maximum yield of the products. Once the limiting reagent is used up, the reaction cannot proceed any further, even if there are still other reactants available. Therefore, the correct choice highlights that it determines the maximum product yield in a reaction.

For example, if you were reacting 2 moles of substance A with 3 moles of substance B, and substance A is the limiting reagent, then even if there were excess amounts of substance B, no more products could be formed once all of substance A is consumed. This concept is fundamental in stoichiometry and allows chemists to calculate how much product can realistically be produced based on the amounts of reactants used.