A lessons learned evaluation captures what worked well and what did not during a change effort, producing insights for future initiatives. ACMP specifies that documenting lessons is essential for organizational learning and improving maturity in change management. While transferring ownership (B) and evaluating outcomes (D) are important closure steps, the action that most directly enhances the organization's ability to handle future changes is conducting and sharing a lessons learned evaluation.

(Reference: ACMP Standard, Process Group 5 -- Close; Activity: Document lessons learned and share with organization.)