What characteristic of explosives relates to their stability against shock or friction?

The characteristic of explosives that relates to their stability against shock or friction is that they should be insensitive to shock or friction. This quality is crucial for ensuring the safe handling, transportation, and storage of explosives. Sensitivity to shock or friction increases the risk of unintended detonation, which can lead to accidents during their use or transport.

Explosives designed to be insensitive are less likely to detonate when subjected to mechanical impacts or friction, thereby enhancing safety for operators and bystanders. This attribute is particularly important for military applications or in environments where explosives may encounter rough handling or unexpected stress.

Options that suggest high sensitivity, the requirement of multiple detonators, or spontaneous ignition indicate characteristics that would actually compromise safety and stability, making them less desirable for practical applications. Therefore, insensitivity to shock or friction is the most appropriate characteristic for explosives aimed at maintaining stability and safety.