A maximizing linear programming problem with variables X and Y and constraints C$1,$ C$2,$ and C$3$has been solved. The dual values $($not the solution quantities$)$ associated with the problem are$$X $=0,$ Y $=$ $$10,$ C$1=$ $$2,$ C$2=$ $$0\mathrm{.}50,$ and C$3=$ $$0.$ Which statement below is true?$$a$.$ One more unit of the resource in C$1$ would reduce the objective function value by $$2.$b$.$ One more unit of the resource in C$2$ would add one$-$half unit each of X and Y$.$c$.$ The resources in C$1$ and C$2$ have not been used up$.$d$.$ The optimal solution makes only X; the quantity of Y must be zero.$$e$.$ All of the above are true.