Final answer:
Receptacles must be GFCI protected when located in a bathroom and outside on the exterior wall of an elementary school, as these areas present a higher risk of electrical shock. GFCIs work by comparing currents and tripping to prevent shocks when a leakage current is detected.
Step-by-step explanation:
Receptacles are required to be GFCI protected when located in specific areas where there is a higher risk of electrical shock due to the presence of moisture or outdoor elements. Both I and II in the provided options are correct. In bathrooms, GFCIs are essential for safety reasons, as they help to prevent electrical shocks by quickly shutting off power to the outlet if a ground fault is detected. Similarly, receptacles outside on the exterior wall of an elementary school must also be GFCI protected to ensure the safety of students and faculty by preventing electrical hazards in outdoor and wet conditions. GFCIs work by comparing currents in the live/hot and neutral wires and will trip if there is a leakage current greater than 5 mA, signifying a potential hazard and preventing harmful shocks.