(40 points) This modeling question deals with a transportation model for mul- tiple products. There are several origins, each of which has available a certain quantity of each product. There are several destinations, each of which requires a certain quantity of each product. Different products can be shipped together, within certain overall capacity limitations. Sets, parameters, and variables for this model could be defined in AMPL as follows: set ORIG ordered; # origins set DEST ordered; # destinations set PROD ordered; # products param avail {PROD, ORIG} >=0; # units available of each product at each origin param require {PROD, DEST) >=0; # units demanded of each product at each destination param limit (ORIG, DEST) >=0; # upper bounds on total units shipped on each route param cost (ORIG, DEST) >=0; # shipping cost per unit var Ship {PROD, ORIG, DEST} >=0; # units of each product to be shipped a: Complete this AMPL statement for the objective function that minimizes total shipping cost: minimize TotalCost: b: Complete this AMPL statement for the supply constraints that ensure that the total units of each product shipped from each origin is at most the number of units available of that product at that origin: subject to Supply {p in PROD, O in ORIG):