What is used to prevent contamination of a potable water system supplying a plumbing fixture such as a galley sink from a backup of sewage sanitary drains?

Correct Answer: Option B — Location of the potable water spigots above the rim of the galley sink.

Under USCG National Maritime Center examination standards, the accepted correct answer is: Location of the potable water spigots above the rim of the galley sink..