Under Standard 1, when developing a real property appraisal, an appraiser must:

Option A: Use all three approaches to value

Option A is incorrect because Standard 1 does not require using all three approaches in every appraisal. While all approaches must be considered, an appraiser only needs to use those approaches that are necessary and applicable for credible results. For example, the income approach may not be necessary for a single-family residence appraisal.

Option C: Use only the approach most relevant to the property type

Option C is wrong because using only one approach, even if most relevant, fails to meet Standard 1's requirement to consider all three approaches. This could result in an incomplete analysis and potentially unreliable valuation conclusions, as different approaches may reveal important market insights or serve as checks against each other.

Option D: Use the approach preferred by the client

Option D is incorrect because Standard 1 requires appraisers to maintain independence and objectivity in their methodology selection. Allowing client preference to dictate approach selection would compromise the appraiser's professional judgment and potentially violate the Ethics Rule regarding independence, impartiality, and objectivity.