Which of the following is a common application for refrigeration systems?

Cooling perishable items is a fundamental application for refrigeration systems. These systems are designed to remove heat from a designated area to lower the temperature, which is essential for preserving the freshness and quality of perishable goods such as fruits, vegetables, dairy products, and meats. By maintaining a controlled, low temperature, refrigeration systems inhibit the growth of bacteria and other pathogens that can spoil food, ensuring longer shelf life and safety for consumers.

Refrigeration plays a crucial role in various industries, including food storage and transportation, where maintaining appropriate temperatures is vital for food safety regulations. Additionally, this application extends beyond just food preservation; it also applies to pharmaceuticals and some chemicals that require stable, cool conditions to maintain their efficacy.

Other options present different functions: heating water is not an application of refrigeration systems, as they are primarily focused on cooling rather than heating. Cooking food generally involves increasing temperatures, which falls under different types of thermal processes. Water purification involves filtration and chemical treatment rather than cooling mechanisms, thus also not aligning with the functionalities of a refrigeration system.