Choose the correct answer from the four options marked A, B, C or D to complete each of the numbered blanks in the following passage

I. Choose the correct answer from the four options marked A, B, C or D to complete each of the numbered blanks in the following passage. 

Everyone wants to reduce pollution. But the pollution problem is as complicated (1) __________it is serious. It is complicated because much (2) __________is caused by things that benefit people. For example, exhaust (3) _________automobiles causes a large percentage of all air pollution. (4)_________ the automobiles provide transportation for millions of people. Factories (5) __________much of the material which pollutes air and water, but factories give employment to a large number of people. 

Thus, to (6) __________or greatly reduce pollution immediately, people would have to stop using many things that benefit them. Most of the people do not want to do that, of course. But pollution can be (7) __________reduced in several ways. (8) _______and engineers can work to find ways to lessen the (9)__________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 (10)__________on certain polluting activities. 

1. A. for B. as C. because D. since
2. A. polluter B. pollutant C. polluting D. pollution
3. A. in B. at C. from D. for
4. A. Therefore B. However C. Moreover D. But
5. A. discharge B. offer C. emit D. dissolve
6. A. cause B. end C. increase D. pause
7. A. increasingly B. hopelessly C. gradually D. dangerously
8. A. Scientists B. Doctors C. Lecturers D. Botanists
9. A. number B. figures C. numbers D. amount
10. A. up B. off C. down D. into