The terms excess reactant and limiting reactant refer to how much of each reactant is available to react. Therefore, by its name we can understand that limiting reactant really limits the reaction, that is, it determines how much product can be made (B).
Excess reactant is also very literal, as it refers to the reactant in excess, that is, the one that is not all used up in the reaction (C).
And Theoretical yield refers to the amount of product that is produced based on the amount of reactants that really react, that is, the amount of product that can be made by the given amount of reactants (A)
In conclusion,
A) Theoretical yield.
B) Limiting reactant.
C) Excess reactant.
