What is its function in the atmosphere

If you are asking "what is the function of the atmosphere," then your answer would be that it protects living things from life threatening radiation from the sun, it traps in some heat so living things don't freeze to death, provides the necessary air living creatures need to survive, allowing light energy to hit the earth for necessary uses, along with allowing multiple weather phenomenons like thunderstorms and cyclones to occur. 

The answer to this question is  c. pharmaceutical accumulation  reclaimed water refers to the water that being used again after it already  used for agricultural purposes.this type of water often contains pharmaceutical accumulation because of the chemical fertilizer that is used for the plants is absorbed into the water.