The correct answer is D) modification. The process by which the temperature and/or moisture characteristics of an air mass changes is called air mass modification. As an air mass moves from its source region, it interacts with the underlying surface and encounters different temperature and moisture conditions, causing its temperature and moisture properties to change through processes such as heating, cooling, evaporation, and condensation. The other answer choices are incorrect because: A) Association refers to the grouping of air masses with similar characteristics. B) Sublimation and condensation are specific phase changes of water, not the overall process of air mass modification. C) Consolidation is not a term related to the changes in an air mass.