Final answer:
A correctly installed three-compartment sink must have air gap backflow prevention to stop contaminated water from backflowing into the clean water supply, ensuring sanitation.
Step-by-step explanation:
A correctly designed and installed three-compartment sink must have a C) Air gap backflow prevention. This type of backflow prevention ensures that there is a physical separation between the end of the water supply line and the flood-level rim of the sink.
By having this air gap, it is impossible for dirty water to backflow into the clean water supply because there is no direct connection that the water can cross. This is crucial in preventing contamination of the water supply, especially in establishments like restaurants and healthcare facilities where sanitation is paramount.
The air gap is a vertical space between the water outlet of the sink and the flood-level rim of the sink. This ensures that even if there is a decrease in pressure in the water supply, wastewater cannot flow back into the clean water supply.
By having an air gap, it prevents any potential contamination of the clean water supply, maintaining the hygiene and safety standards required for a sink used in food preparation or commercial settings.
Therefore the correct Option is C) Air gap backflow prevention.