I believe that the answer is biosphere<span />
Answer:
The three most important sources of environmental problems are 1) market failure, 2) the tragedy of the commons, and 3) the underprovisioning of public goods
Explanation:
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<span>The most common contaminant to be found in drinking water is microorganisms, nitrate and arsenic. Though water quality and monitoring has come a long way over the past few years, viruses, bacteria and protozoa like giardia lambia can be found in the water and often leads to wide spread illnesses.</span>
Answer: coral reefs act as a filtering system .
Explanation:
