A dishwasher stores a bottle of degreaser on a shelf directly above a bin of fresh onions. This creates a risk of which type of contamination?

解析

A cleaning chemical stored above food creates chemical contamination if the degreaser leaks, drips, or splashes onto the onions. Chemicals must be kept in a separate area, below and away from food, utensils, and single-service items (FDA Food Code §7-201.11). Nothing here involves a pathogen, so it is not biological contamination; nothing involves a foreign object such as glass or metal, so it is not physical contamination; and degreaser is not one of the Big 9 allergens, so allergen cross-contact does not apply. Each option names a real control, but only one names the hazard this storage error creates.