Final answer:
A callus should be treated during a pedicure by smoothing and reducing it with a foot file, avoiding invasive methods like using a credo blade.
Step-by-step explanation:
The question "How should a callus be treated during a pedicure?" addresses the correct approach to dealing with hardened skin during a pedicure. The appropriate method is to smooth and reduce the callus using a foot file. This is a gentle and safe way to manage calluses without being invasive. Using a credo blade is generally not recommended as it can be unsafe and should only be performed by a medical professional if required. Doing nothing isn't helpful if the person desires treatment, and recommending a client to a physician is only necessary if there are signs of infection or other medical concerns.