After Testing Each Unused Cell by the Stepping-Stone Method in the Transportation

Multiple Choice

After testing each unused cell by the stepping-stone method in the transportation problem and finding only one cell with a negative improvement index

A) once you make that improvement, you would definitely have an optimal solution.
B) you would make that improvement and then check all unused cells again.
C) you could stop because you already had the optimal solution.
D) you should check to be sure that you don't have to add a dummy source or dummy destination.