马上考了，帮看看这道GMATprep CR题？谢谢！

For years the beautiful Renaissance buildings in Palitito have been damaged by exhaust from the many tour buses that come to the city. There has been little parking space, so most buses have idled at the curb during each stop on their tour, and idling produces as much exhaust as driving. The city has now proveded parking that accommodates a third of the tour buses, so damage to Palitito's buildings from the buses' exhaust will diminish significantly.

which most supports?

B. Palitito's Renaissance buildings are not threatened by pollution other than engine exhaust.

C. Tour buses typically spend less than one-quarter of the time they are in Palitito transproting passengers from one site to another.

A, D & E 很无关，排除。

我选择B，请问为什么答案是C？

B是直接削弱前提,GMAT中一般不会这样. C解释因果关系 加强逻辑练故选