Which flare cartridge will ignite when exposed to oxygen?

The M211 flare cartridge is specifically designed to ignite when exposed to oxygen. This feature is crucial for its function and effectiveness as a signaling device. The chemical composition within the M211 is formulated to react with oxygen, providing a reliable source of illumination and visibility when deployed.

In contrast, the other options, while they may serve similar purposes for signaling or illumination, do not possess the same reactive properties with oxygen as the M211. Each flare cartridge has unique specifications and functionalities, which are important to understand in the context of usage scenarios, but the M211 stands out for its capacity to ignite upon oxygen exposure, ensuring it can be effectively utilized in various atmospheric conditions.