Comprehensive and Detailed Step-by-Step Explanation: Ifmeasurable benefitswerenot defined, the organizationcannot assess whether the system achieved its intended goals, making it the mostcriticalissue. * Measurable Benefits Not Defined (Correct Answer - D) * No clear KPIs or success metricsmeans no way toevaluate ROI. * Example:A company implementsan ERP systembut has no performance indicators to measure success. * No Lessons Learned (Incorrect - A) * Important but doesnot impact system effectiveness. * Missing Dashboard Deliverables (Incorrect - B) * A reporting issue,not a strategic failure. * Budget Overrun (Incorrect - C) * A financial concern butnot as critical as system success measurement. References: * ISACA CISA Review Manual * COBIT 2019 (Project Governance)