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.