GWD-6-33,为什么不选B--急!!!

GWD6-Q33:

Crowding on Mooreville’s subway frequently leads to delays, because it is difficult for passengers to exit from the trains.  Subway ridership is projected to increase by 20 percent over the next 10 years.  The Metroville Transit Authority plans to increase the number of daily train trips by only 5 percent over the same period.  Officials predict that this increase is sufficient to ensure that the incidence of delays due to crowding does not increase.

Which of the following, if true, provides the strongest grounds for the officials’ prediction?

1. By changing maintenance schedules, the Transit Authority can achieve the 5 percent increase in train trips without purchasing any new subway cars.
2. The Transit Authority also plans a 5 percent increase in the number of bus trips on routes that connect to subways.
3. For most commuters who use the subway system, there is no practical alternative public transportation available.
4. Most of the projected increase in ridership is expected to occur in off-peak hours when trains are now sparsely used.
5. The 5 percent increase in the number of train trips can be achieved without an equal increase in Transit Authority operational costs.

请NN帮忙,B错在哪里啊?谢谢!

Answer should D. It states that the ridership is projected to increase in off-peak hours, which mean even current subway may accommodate the increase, and 5 percent daily train trips increase will help alleviate the crowding at the rush hours. So support the officials' prediction.

Answer B doesn't provide any supportive information on officials' arugument. The problem subway is currently suffering is the crowding inside of subway, so bus trips on routes increase won't help at all.

thank you