4. The following figure gives the mileage of the feasible links connecting nine offshore natural gas wellheads with an inshore delivery point. Because wellhead 1 is the closest to shore, Delivery point it is equipped with sufficient pumping and storage capacity to pump the output of the remaining eight wells to the delivery point. Determine the minimum pipeline network that links the wellheads to the delivery point. 15 14 4 M 6 10 5 13 15 20 12 Answer (max 15 points): Delivery point 5 2 15 9 14 20 6 3 5 10 5 13 15 20 5 8 12 7 3 6