Potash is produced at 3 mines in Saskatchewan: mine A, mine B, and mine C. The potash is shipped to railway depots 1 and 2. Daily production at the mines is 350 tons from mine A, 400 tons from mine B, and 150 tons from mine C. All production must be shipped to one of the railway depots which have the following daily capacity: 200 tons at depot 1 and 800 tons at depot 2. The company uses a transportation LP to decide how much to ship from each factory to each depot, to minimize weekly shipping cost. In this LP, Xij denotes the number of tons shipped from mine i (i=A,B,C) to depot j (j=1,2).

If all direct shipments between mines and depots are replaced by shipments to and from a single transshipment node, how many decision variables will be required in the LP formulation, compared to the original problem?

a) The same number of decision variables.

b) Two fewer decision variables.

c) Two more decision variables.

d) One fewer decision variable.

e) One more decision variable.