Final answer:
A receptacle under the kitchen counter used for a disposal must be GFCI protected to prevent electrical shock due to potential leakage currents, as required by the National Electrical Code.
Step-by-step explanation:
The requirement for a Ground Fault Circuit Interrupter (GFCI) protection in kitchens is to ensure safety by preventing electrical shocks that may occur due to leakage currents. Kitchens, being places where water use is common, are areas of the home where GFCI protection is especially important. Under the National Electrical Code (NEC), GFCI protection is required for all receptacles that serve countertop surfaces in a kitchen, and this would typically include a receptacle used to supply power to a disposal unit located under the kitchen counter. Since a disruption in the balance between the live/hot and neutral currents signals a potential leakage and a path of current that could cause harm, the GFCI would trip to interrupt the circuit if it detects a leakage current greater than 5 mA.
Therefore, the correct answer to whether a receptacle under the kitchen counter used to supply power to a disposal must be GFCI protected is: a. Yes.