Here are the best answers for each blank:

1. C. group
2. C. spoil
3. B. polluting
4. B. to reduce
5. C. harmful
6. B. for
7. C. as
8. B. because
9. B. instead
10. B. preventing
11. C. onto
12. D. out of
13. C. from
14. C. in
15. C. would
16. C. less

Please review the context of each question to ensure clarity and accuracy.