What formula would you enter in "objective function cell" in this excel model?

A B C D E F G H J K L M Unit Net Supply/ 3 X Flow from Node Yield Flow into Node Cost Nodes Flow Demand Crude A 0.90 3 Refinery 1 15 1 Crude A 120 Crude A 0.85 4 Refinery 2 13 2 Crude B 60 2 Crude B 0.80 3 Refinery 1 9 3 Refinery 1 0 2 Crude B 0.85 4 Refinery 2 11 4 Refinery 2 0 3 Refinery 1 0.95 5 Lube Oil 4 5 Lube Oil 75 3 Refinery 1 0.90 6 Gasoline 7 6 Gasoline 50 10 3 Refinery 1 0.90 7 Diesel 8 7 Diesel 25 11 4 Refinery 2 0.90 5 Lube Oil 3 12 4 Refinery 2 0.95 6 Gasoline 9 13 4 Refinery 2 0.95 7 Diesel 6 14 15 Total costIll. What formula would you enter in "objective function cell" in this Excel model? BI a. SUMPRODUCT(D4:D15,A4:A15) b. SUMPRODUCT(H4:H13,A4:A13) c. SUMPRODUCT(H6:H15,A6:A15) d. SUMPRODUCT(H6:H15,A6:A15)