How should a Food Manager check the temperature of milk upon delivery?

To effectively check the temperature of milk upon delivery, it is essential to ensure that the thermometer is placed in a location where it can accurately measure the product's temperature without interference. Placing the thermometer between containers of milk allows for air to circulate while still closely measuring the temperature of the milk itself. This method is beneficial in getting a quick assessment and ensuring that the milk is at a safe temperature, especially considering that milk is a temperature-sensitive product that can spoil if not handled properly.

The other options do not provide an effective means of checking the milk's temperature. For example, placing the thermometer in the delivery truck would likely provide an inaccurate reading, as the truck’s ambient temperature does not reflect the milk's actual temperature. Piercing one container and emptying milk into different containers are methods that can lead to cross-contamination or do not provide a reliable measurement of the core temperature. It's crucial to maintain food safety standards, and using the thermometer between containers represents a practical approach while still ensuring the integrity of the milk product.