单选题
[填句补文]The acid rain（酸雨）is said to be caused by pollution from oil wells in the Gulf of Mexico. Car exhaust gases are also a problem. Local volcanic eruptions make the problem even worse. Nevertheless， with enough money and effort， researchers say that many of the problems could be solved and the rate of erosion reduced. ________.
A、The problem， however， is not just a European one.
B、That is enough to have caused some of the ancient carvings to become seriously damaged already.
C、However， the Mexican government does not have enough money to do the work， and needs to spend what money it has on the Mexican people.
D、Acid rain is how a familiar problem in the industrialized countries in Europe.
正确答案：C
答案解析：前文提到完成这项工作需要很多的钱，答案转折说到了墨西哥没有这么多的钱去做。两句之间有隐含的逻辑关系。