Complete the passage with the given words

Environmental pollution is a term that (21) ______ to all the ways by which man pollutes his surroundings. Man dirties the air with exhaust gases and smoke, poisons the water with chemicals and (22) _____ substances, and damages the soil with too many fertilizers and pesticides. Man also pollutes his surroundings (23) _____ various other ways. For example, people ruin natural beauty by leaving junk and litter on the land and in the water.

Environmental pollution is one of the most serious problems facing mankind today. Air, water and soil are necessary to the (24)_______of all living things. Badly polluted air can cause illness, and (25) __________ death. Polluted water kills fish and other marine life. Pollution of soil reduces the amount of land that is available for (26) _________ food. Environmental pollution also ugliness to man’s natural beautiful world.

Câu 21 : (21) _________

A. means

B. refers

C. provides

D. reduces