Read and choose the best answer to complete the passage

Exercise 8:Read and choose the best answer:
Hi Liam,
How are you? I’m happy to share with you some good news about my village. There have been some changes (1)_____ your visit last year.
Last week I came back to my village and was really surprised. You know what? The lake is not (2)_____ anymore. The factory has installed a new filtration system to treat the (3)_____ waste. I saw lots of small fish in the lake and wild ducks swimming in the water. Besides, they have planted trees around the factory to (4)_____ air pollution.
Since some villagers are in the habit of littering, people have placed dustbins in various places. This has (5)_____ in a much cleaner environment. My grandparents say that at weekends the villagers also go around the village together to (6)_____ rubbish.
What about your neighbourhood? Has anything been done to make it cleaner? Tell me all about it in your next email.
Bye for now,
Mi
1.A.for              B.since             C.after               D.before
2.A.pollute       B.polluting       C.pollutant         D.polluted
3.A.chemical    B.chemistry      C.physics           D.physical
4.A.increase      B.rise                C.reduce            D.fall
5.A.caused        B.led                 C.made               D.resulted
6.A.collect       B.pick               C.get                    D.take