Final answer:
To clean a foot spa after use, a foot rinse should be performed, as it is specifically meant to remove residue and contaminants. Treatments like foot scrubs, masks, and soaks are not designed for cleaning the spa itself. Ensuring a clean foot spa is critical for hygiene and client safety.
Step-by-step explanation:
The question pertains to the proper hygiene practices in a spa, notably how to remove the residue of pedicure products from a foot spa. The correct answer to the question is Option 4: Foot rinse. A foot rinse is the process used to thoroughly clean and remove any product residue, debris, or contaminants from a foot spa after a pedicure. The other options, such as foot scrub, foot mask, and foot soak, are treatments applied during the pedicure process, rather than cleanup methods. A proper foot rinse often involves draining the foot spa, cleaning with disinfectant, rinsing with clean water, and drying to ensure that the next client has a hygienic experience.