What is one advantage that a train might have over a bus in terms of mass transportation trade-offs.

A)  Train systems cost less to develop and maintain than bus systems. 
B)  Train schedules and routes tend to be more flexible than those of buses. 
C)  Trains are relatively immune to rush-hour traffic problems. 
D)  Trains are easier to reroute should route-blockage occur through accidents or construction.

Trains are able to operate on their own dedicated tracks, separate from other vehicles, which means they are less likely to be affected by rush-hour traffic problems. Buses, on the other hand, must share the road with other vehicles, which can slow them down and cause delays. Additionally, trains are typically able to carry more passengers than buses, which can help to alleviate congestion during peak travel times. While trains may be more expensive to develop and maintain than buses, the advantages in terms of speed and efficiency may make them a better choice for mass transportation in some cases. However, trains may not always be more flexible than buses, as buses can be rerouted more easily if necessary. Ultimately, the choice between trains and buses will depend on a variety of factors, including the specific transportation needs of a given community or region.