A vulnerability management process is a process that identifies, analyzes, prioritizes, and remediates the vulnerabilities in the IT systems and applications. The effectiveness of a vulnerability management process can be measured by the key performance indicators (KPIs) that reflect the achievement of the process objectives and the alignment with the enterprise’s risk appetite and tolerance. The best KPI to measure the effectiveness of a vulnerability management process is the percentage of vulnerabilities remediated within the agreed service level. This KPI indicates how well the process is able to address the vulnerabilities in a timely and efficient manner, and reduce the exposure and impact of the risks associated with the vulnerabilities. The other options are not as good as the percentage of vulnerabilities remediated within the agreed service level, as they may not reflect the quality or timeliness of the remediation actions, or the alignment with the enterprise’s risk appetite and tolerance. References = Risk and Information Systems Control Study Manual, 7th Edition, Chapter 4, Section 4.3.2.1, pp. 171-172.