Change impact assessmentevaluates the depth and breadth of the change across processes, people, technology, and culture. ACMP specifies this activity determinessize, scope, timing, and complexityof the effort. Stakeholder identification (B) and sponsorship assessment (C) are complementary but not sufficient to define overall impact. Benefits realization (A) occurs later during execution. Thus, option D directly corresponds with this critical evaluation activity.
(Reference: ACMP Standard, Process Group 1 - Evaluate; Activity: Conduct change impact assessment.)