Which of the following combination of fixtures must be fitted with an air break?

An air gap is a vital feature designed to prevent backflow and contamination in plumbing systems, particularly in food service settings. The correct combination of fixtures that must be fitted with an air break is pot wash and culinary sinks.

Both pot washing and culinary sinks are used for food preparation and cleaning large pots and equipment, which often results in water containing food particles, grease, and other residues. If there's a backflow, it could lead to contamination of the clean water supply. An air break provides a physical separation that stops any potential backflow by ensuring that wastewater cannot siphon back into the clean water system, thus maintaining sanitation and health standards essential in food handling.

In contrast, while hand sinks and dishwashers, ice machines and beverage dispensers, or prep sinks and washbasins have their sanitation requirements, they do not necessarily require an air break in the same way that pot wash and culinary sinks do. The purpose of an air gap is specifically related to fixtures that handle dirty water and have a higher risk of contaminating the potable water supply.