What must the designated Flight Attendant verify regarding the lithium-ion containment bag during preflight?

The designated Flight Attendant must verify the presence and sealing of the lithium-ion containment bag during preflight as a critical safety measure. This verification ensures that the bag is not only available on board but also properly sealed to contain any potential fires or thermal events that may occur due to lithium-ion batteries. Ensuring the bag is present contributes to the aircraft's safety protocols, particularly in the management of hazardous materials on board. If the bag is not sealed, it may not contain harmful substances effectively, which could pose a risk during the flight.

While other aspects, such as color coding, expiration, and weight, can be important in different contexts, the critical point during preflight checks for safety is to ensure the bag is correctly sealed and present to mitigate risks associated with lithium-ion battery incidents.