why in step 4 and five, the branch 2-5 is ignore? since if 4-5 is more than 4, 2-5 is the possible answer?

Problem Statement A salesman for Healthproof Pharmaceutical Company travels each week from his office in Atlanta to one of five cities in the Southeast where he has clients. The travel time (in hours) between cities along interstate highways is shown along each branch in the following network: co 6 3 2 NO 5 7 2 5 3 A. Determine the shortest route from Atlanta to each of the other five cities in the network. 7 Solution Step 1 (Part A): Determine the shortest Route Solution 1. Permanent set Branch Time 1-2 1-3 5 1-4 2. Permanent set Branch Time {1,2} 1-3 5 1-4 7 2-5 11 3. Permanent set Branch Time {1,2,3} 1-4 2-5 11 3-4 7 4. Permanent set Branch Time {1,2,3,4} 4-5 10 46 9 5. Permanent set Branch Time {1, 2, 3, 4, 6) 45 IC 6-5 13 6. Permanent set {1, 2, 3, 4, 5, 6)