Read the passage and choose the best word (A; B or C) to each space

Read the passage and choose the best word (A, B or C) to each space. (1pts)
   People need to breathe. If they don’t breathe, they (1)…………die. But how  clean is the air people breathe? If they breath  (2) …………air, they will have breathing problems and become ill. Plants and animals need (3)…………… air, too. A lot of things in our lives create harmful gases and (4)………….the air dirty like cars, motorbikes and factories. Dirty air is called polluted air.
1. A. must                       B. will                 C. are                       D. is
2. A. clean                      B. clear                C. dirty                     D. pollution
3. A. dirty                       B. clean               C. safe                       D. A & B
4. A. make                      B. get                   C. let                         D. give