What is a critical characteristic of the M211 flare in handling processes?

The critical characteristic of the M211 flare in handling processes is that it can ignite upon exposure to oxygen. This property is essential for understanding how to safely manage and deploy the flare. The ignition upon exposure to oxygen highlights the need for careful handling and storage to prevent unintentional ignition, which could lead to hazardous situations. Recognizing this characteristic ensures that individuals working with the M211 flare have the necessary precautions in place to avoid accidents and ensure safety during its use.

Considering the other choices, while aspects like weight and lifespan may be relevant to specific operational contexts, the ability to ignite in contact with oxygen directly informs safety protocols and handling procedures necessary for safe operations with the flare.