Hi chetan86,

CR questions that are based on a "plan" always have a base-assumption that everything else will "stay the same." In that way, the plan should work because the author doesn't have to take anything else into account.

Here, the Governor has a plan:

The Facts:
-The bridge is need of repairs that will cost about $30 million.
-Over 1 million vehicles cross the bridge each day.
-The city plans to charge a $1 toll to cross the bridge.

The Conclusion:
-The toll will raise enough money to repair the bridge within a month.

This plan seems reasonable, IF you assume that everything stays the same. IF a million vehicles continue to cross the bridge AND pay the toll EACH DAY, then it's reasonable to conclude that the plan will raise $1 million a day and $30 million in a month.

The correct answer C confirms that people who would normally drive across the bridge won't change their habits (and use mass transit; re: a bus). You asked about answer B, but the idea that the toll might cause a hardship on the commuters is irrelevant. Even if it DID cause a hardship, as long as the drivers continue to use the bridge then the plan would work.

GMAT assassins aren't born, they're made,
Rich