Responsibility assignment in SAP OCM depends on project scale. Option A is correct because large projects require specialized expertise, so a dedicated change manager or team is typical to handle complexity. Option C is correct as small projects often lack resources for a separate change manager, so the project manager assumes this role. Option B is incorrect—business leaders may support change but are not typically responsible for managing it, as this requires specific OCM skills. Option D is incorrect; the project sponsor provides oversight and support, not direct responsibility for execution, regardless of size.

Extract from SAP OCM Concepts: SAP Activate recommends tailoring OCM roles to project size, with dedicated resources for large implementations and consolidated roles for smaller ones (SAP OCM Framework).