Ground-fault circuit interrupter protection is available in which of the following types of equipment or products?

Ground-fault circuit interrupter (GFCI) protection is a critical safety feature designed to prevent electrical shocks by quickly shutting off power in the event of a ground fault. This type of protection can be found in a wide variety of equipment and products, making it versatile for different environments.

GFCI protection is available not only in outdoor products, which may be exposed to moisture and thus have a higher risk of ground faults but also in residential settings overall, including indoor areas where water is present, such as kitchens and bathrooms. Additionally, portable devices, like GFCI plugs and extension cords, are designed to provide GFCI protection in temporary setups or outdoor conditions.

So, the correct option highlights the adaptability of GFCI technology across various contexts—outdoor, residential, and portable—demonstrating its essential role in enhancing electrical safety in numerous scenarios. This makes it evident why the answer is inclusive of all these categories, indicating that GFCI protection is not restricted to a specific type of equipment or setting.