4. (20 pts) One aspect of software-defined data routing is to select a cost-optimal end-to-end path for data transport, where the per-hop link costs depend on the data-flow characteristics itself. This is unlike the traditional hop-count based routing of data (which is analogous to choosing a path with the shortest physical distance without worrying about the volume of traffic along that path). One case of flow-dependent costs incurred along a routing path is the data delays induced by traffic congestion on the network links (due to excessive data traffic flow). Figure 3 shows a multi-hop data routing scenario with two alternate paths I and II, in the face of variable per-hop delays incurred due to data-traffic. Show mathematically how the route selection mechanism determines whether path-I or path-II is the best to carry the traffic. You need to show different values of traffic-flow parameter 0.0