What test examines whether a system will perform automatically should everyone let go?

The correct choice is the whistle test, which is designed to evaluate whether a system can operate autonomously in the event that all personnel or operators disengage or let go. This test is crucial for assessing the reliability and safety of a system, particularly in rescue operations where human interaction may not always be guaranteed.

In technical rescue contexts, ensuring that a system has the capability to function independently is essential to prevent catastrophic failures or accidents. The whistle test simulates a scenario where manual control is lost, allowing evaluators to determine if the system is designed to activate or maintain its functions automatically, thereby safeguarding individuals who may rely on this equipment during a rescue.

The other options, while they may sound relevant in different contexts, do not specifically address the automatic functionality of a system when human input is no longer present. The critical point test typically evaluates the limits of a system or material rather than its automated response. The system deficiency test focuses on identifying faults within the system, and the weak link test examines the weakest point in a series of components rather than the system's autonomous capabilities.