IMO, the main reason why C is incorrect is because it is out of scope. The way in which the bridge maintenance project is financed has got nothing to do with the current proposal. There is no direct cost-benefit link here.

On the other hand, D tells us that although automobile users will have to pay the toll, they are in fact getting something in return (less congestion, so shorter commute times perhaps?).

hth

-BM-

Option D looks good than other answers