What must the flight attendant do after the predeparture announcement on the CRJ 200?

After the predeparture announcement on the CRJ 200, it is essential for the flight attendant to demonstrate the oxygen mask and seat belt operation. This demonstration is crucial for passenger safety, as it ensures that all occupants understand how to properly use the safety equipment in case of an emergency. The visibility and clarity of this demonstration help reinforce safety protocols, allowing passengers to feel more secure during the flight.

While other responsibilities are part of a flight attendant's role, such as taking their jumpseat, serving beverages, or checking the aircraft's weight and balance, these actions are not as immediate or critical immediately after the predeparture announcement. The focus on safety and preparedness directly connects to the importance of demonstrating the use of safety equipment right before the flight.