When a practitioner uses an electric file on a foot callus, what condition should the client's foot be in?

Using an electric file on a foot callus is most effective when the client's foot is soft and dry. This condition allows for better control and precision while filing, as a softer callus can be more easily shaped and smoothed. When the calluses are softened, the electric file can remove them efficiently without causing unnecessary trauma to the surrounding skin.

In contrast, if the foot is wet and slippery, the file may not be able to grip the surface properly, leading to ineffective filing and potential slips that could cause injury. A cold and numb foot would indicate inadequate circulation or improper preparation, which can increase the risk of accidents and decrease the practitioner's ability to assess the area effectively. Lastly, while a foot that is rough and calloused is indeed a target area for treatment, it's essential for the callus to be prepared to a soft state to achieve the best results with the electric file.