Final answer:
According to USPAP, a Supervisory Appraiser is required to create a workfile for an appraisal assignment at the time the assignment is accepted.
Step-by-step explanation:
According to the USPAP (Uniform Standards of Professional Appraisal Practice), a Supervisory Appraiser is required to create a workfile for an appraisal assignment at the time the assignment is accepted. This means that as soon as the appraiser accepts the assignment from the client, they must start assembling a workfile that documents their research, analysis, and conclusions.
The workfile should include relevant information about the property, data sources, calculations, and any other supporting documentation. This documentation helps ensure transparency, accountability, and accuracy in the appraisal process.
Therefore, the correct answer is C. At the time the assignment is accepted.