Which of the following describes a sanitary sewer?

A sanitary sewer is specifically designed to transport wastewater from residential, commercial, and industrial sources to a treatment facility. This wastewater includes water from sinks, showers, toilets, and appliances, which can contain various contaminants and pathogens. The primary goal of a sanitary sewer system is to safely convey this wastewater for proper treatment, ensuring that it is processed and cleaned before being released back into the environment or reused.

The other options do not accurately define a sanitary sewer. Clean water transportation refers to potable water systems, not wastewater. Systems that handle stormwater runoff are focused on managing rainwater and preventing flooding, which differs from the purpose of a sanitary sewer. Finally, a drainage system specifically for rainwater does not account for the wastewater collected in a sanitary sewer, which is integral for public health and environmental protection. Thus, option C captures the essential function of a sanitary sewer accurately.