Name the primary function of a life jacket.

The primary function of a life jacket is to keep a person afloat in water. Life jackets are designed with buoyant materials that help individuals remain on the surface, which is critical in preventing drowning. This flotation capability is essential during emergencies where a person may end up in the water unexpectedly.

While warmth in cold water, swimming assistance, and signaling for help are important considerations related to safety on the water, they are secondary to the main purpose of a life jacket. A life jacket specifically addresses the immediate need for buoyancy and flotation, allowing a person to conserve energy and stay safe until rescue can occur.