An extraordinary assumption may be used in an assignment only if:

• A. Required to develop credible results.
• B. At the appraiser's discretion.
• C. At the client's request.
• D. If the appraiser suspects it.

Answer: (A)

An extraordinary assumption is something the appraiser assumes to be true for the purposes of the assignment because it’s necessary to complete the analysis and develop credible results. It isn’t a choice or a whim; it must be required to achieve a credible conclusion and grounded in a credible basis. If this assumption proves false, the conclusions could be impacted, so the appraiser should disclose the assumption and its potential effect on the results.

That’s why this option is best: extraordinary assumptions may be used only if they are required to develop credible results. It isn’t a matter of the appraiser’s discretion, nor something done simply at the client’s request or merely because the appraiser suspects something.