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

An extraordinary assumption is a recognized concept in appraisal practices and refers to an assumption that, if found to be false, could alter the appraiser's opinions or conclusions. In order for an extraordinary assumption to be appropriately employed in an appraisal assignment, it is essential that it is necessary to develop credible results.

Using extraordinary assumptions allows appraisers to make necessary assumptions about certain conditions that are not known or verifiable at the time of appraisal. This is particularly important when the assumption directly impacts the credibility of the conclusions drawn from the appraisal. For instance, if an appraiser assumes that a property meets zoning requirements when there is no definitive evidence, this assumption must be justified and necessary to reach credible results.

While the other options may seem relevant, they do not capture the primary necessity for which extraordinary assumptions are intended. For instance, maximizing the report's value or simplifying the appraisal process does not inherently contribute to the credibility of results, which is essential for ensuring that the appraisal serves its intended purpose reliably. Therefore, the correct understanding hinges on the necessity of the extraordinary assumption to produce credible appraisal results.