Chọn từ phù hợp nhất để điền vào chỗ trống trong đoạn văn sau.

One of the reasons why our environment is (46) _____ is that each household produces a lot of rubbish every day. In order to reduce the pollution, we need to increase the volume of rubbish that is recycled because we cannot carry on (47) _____ and burning rubbish forever. This means that we should reduce the (48) _____ of rubbish we produce and encourage people to reuse and recycle. We also need to have a strict punishment for those (49) _____ throw rubbish on the streets, in the ponds, rivers and seas. Besides, we ourselves should be aware (50) _____ keeping our environment green, clean and beautiful.