Which of the following is a washer-sterilizer used for instrument cleaning?

The correct choice is mechanical decontamination, as it specifically refers to a method that utilizes equipment, such as a washer-sterilizer, to clean surgical instruments effectively. Mechanical decontamination employs processes that incorporate water, detergents, and sometimes elevated temperatures to physically remove debris, blood, and other contaminants from instruments. This method is crucial in maintaining the integrity and functionality of surgical tools while ensuring they are safe for patient use.

In contrast, sonic cleaning involves the use of ultrasonic waves to agitate a cleaning solution, which can effectively clean instruments but does not classify as a washer-sterilizer. Alcohol immersion may disinfect surfaces but is not specifically designed for thorough cleaning or sterilization of complex surgical instruments. Ultraviolet light treatment is an effective method for disinfection but does not replace the need for physical cleaning and the thorough decontamination process that mechanical methods provide. Thus, mechanical decontamination stands out as the most suitable method for cleaning surgical instruments using washer-sterilizers.