Which of the following is considered a potentially hazardous food?

Milk is considered a potentially hazardous food because it provides an environment conducive to the growth of pathogenic bacteria when not properly stored or handled. These bacteria thrive in the temperature range known as the "danger zone" (40°F to 140°F) where milk can spoil quickly if left unrefrigerated.

In contrast, apples, potatoes, and bread typically have characteristics that make them less prone to support rapid bacterial growth. For instance, apples and potatoes are often stored at cooler temperatures and have natural properties that inhibit bacterial growth. Bread, while it can mold, generally has a more stable shelf life when stored properly and does not support the growth of harmful bacteria in the same way that milk does. Thus, milk stands out as a food that needs careful consideration regarding food safety.