If the Organizers want to ensure that all participants travelling from S to T take the same time (travelling time and task time combined) regardless of the route they choose and the street from B to C is under repairs (and hence unusable), then a feasible set of task time (in hours) at junctions A, B, C, and D respectively to achieve this goal is:
As B - C is unusable, S - B - C - T is not possible.
The other possible ways are : S - A - T, S - B - A - T , S - D - T, and S - D - C - T
From these if we apply all the options:
Both option (b) and (c) are true, as in both the cases total time is same for each of the four routes.
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