Final answer:
When an appraiser says 'the whole is worth more than the sum of its parts', they are referring to assemblage in real estate appraisal.
Step-by-step explanation:
When an appraiser says 'the whole is worth more than the sum of its parts', they are most likely referring to A. assemblage. Assemblage is a term used in real estate appraisal to describe the value of a property as a whole, which may be higher than the combined value of its individual components. This concept recognizes that the combination and interaction of different elements can create a synergistic effect that increases the overall value.