Everyone wants to reduces pollution but the pollution ……. is as complicated as it is serious. It is complicated because much pollution is caused by things that benefit people. For example, …….. from automobiles causes a large percentage of air pollution. But the automobile provides transportation for millions of people. Factories ...(?) many of materials that pollute the air and water, but factories give employment to a large number of people. Thus, to end or greatly reduce pollution immediately, people would have to stop using many things that …….. them. Most of the people do not want to do that, of course. But pollution can be gradually reduced in several ways. Scientists and engineers can work to find ways to lessen the amount of pollution that such things as automobiles and factories cause. Governments can pass and enforce laws that require businesses and individuals to stop, or cut down on certain polluting activities. A.discharge B.cause C.offer D.bring