When assessing a safety-critical system, which metrics are most appropriate for determining if the test objective has been met?

In the context of assessing a safety-critical system, the most important aspect is to ensure that the system is functioning as intended without posing any risk to safety. Therefore, the metrics that best reflect whether the test objectives have been met in such systems focus on the outcomes of tests that assess the safety and reliability of the system.

The option indicating "Regression tests run and passed in systems testing" highlights a critical facet of ensuring the ongoing correctness and safety of a system. Regression tests ensure that previously functioning features continue to perform correctly after changes or updates to the system. In safety-critical systems, any changes—even minor ones—could introduce risks, so confirming that these key tests run and pass indicates that the system remains safe and reliable.

In safety-critical environments, simply running tests or counting incidents may not necessarily provide a clear picture of safety assurance. Therefore, while understanding the performance of closed incidents and overall test execution metrics is important, the primary focus should be on regression testing outcomes that directly relate to maintaining ongoing safety and reliability standards. This especially applies in safety-critical sectors, where the consequences of failure can be severe.