There is a planned upgrading programme for the national healthcare security in the Staffordshire County which is made up of the following districts: East Staffordshire Lichfield Newcastle-under-Lyme South Staffordshire Stafford Staffordshire Moorlands Tamworth There is a community hospital in each of the districts above. East Staffordshire district's community hospital will host the health record server for residents in the county. Dedicated underground cables will be laid to link up all the community hospitals in the county which will eventually be able to access the server hosted at East Staffordshire. Table 3-1 shows the costs incurred (in thousands of pounds) to connect the hospitals. Note that values in the lower triangle (grey cells) of Table 3-1 are omitted for brevity, and they are symmetric to the values in the upper triangle; for example, the cost between Newcastle-under-Lyme and East Staffordshire is the same as the cost between East Staffordshire and Newcastle-under-Lyme. Also note that it is not feasible for direct connection between some districts due to geographical constraints (e.g., between East Staffordshire and Lichfield). Table 3-1 And Between East Staffordshire Lichfield NewcastleunderLyme South Staffordshire Stafford Staffordshire Moorlands Tamworth East Staffordshire - - 25 50 42 - 70 Lichfield - 35 - 46 32 - Newcastle-underLyme - 40 - - 35 South Staffordshire - - - 60 Stafford - 28 62 Staffordshire Moorlands - 36 Tamworth - (a) Draw an appropriate network model using the information in Table 3-1 and propose a possible cost optimal solution to the case.