The correct answer is C. sewage discharge.
Even though there might even be no harmful pathogens at all if there isn't any waste, it is correct because it is implied that there is waste such as fecal matter inside of the sewage discharge.
Answer: With the development of powerful microscopes, scientists discovered many single-celled organisms that didn't fit into any of Linnaeus' kingdoms. As a result, a new taxon, called the domain, was added to the classification system.
Explanation:
