A plumber is installing a dishwasher in a residence. To prevent the backflow of contaminated water from the sink drain into the dishwasher, which of the following is the most effective and commonly code-required method?
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A
A high loop in the drain hose secured to the underside of the countertop.
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B
An air gap fitting mounted on the countertop or sink deck.
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C
A check valve installed in the dishwasher's drain line.
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D
Connecting the drain hose to the garbage disposal below the sink's flood level rim.