For what specific reason is the “space blanket” kept in a CLS bag?

The specific reason the "space blanket" is kept in a CLS (Combat Lifesaver) bag is to warm up the casualty to prevent hypothermia. These thermal blankets are designed to reflect body heat back to the casualty, helping to maintain their core temperature in emergency situations. This is crucial, especially in outdoor settings or environments where the temperature may drop quickly. Hypothermia can set in rapidly, making it essential to use all available resources to keep the casualty warm while awaiting further medical assistance.

The other options may seem plausible but do not properly reflect the primary function of the space blanket in this context. For instance, while medical supplies are important, the space blanket's primary role is not related to carrying supplies or maintaining sterility.