What must be done before take-off and prior to landing if seats are blocked off?

Before take-off and prior to landing, it is crucial for safety and compliance with regulations that passengers occupy their assigned seats. This ensures that all passengers are accounted for and securely positioned, which is essential during critical phases of flight like take-off and landing. When passengers are in their assigned seats, cabin crew can better manage the cabin environment, ensuring that everyone is properly secured with seatbelts fastened and that the cabin is in a safe condition.

Having passengers in their assigned seats also allows for efficient communication and monitoring by the flight attendants, enhancing overall safety. Blocked seats may be due to safety protocols, weight distribution, or other operational reasons, but it is necessary to ensure all passengers are seated as originally assigned before these critical flight phases.

The other options may distract from the focus on safety and order in passenger seating, but ensuring passengers return to assigned seats is paramount for effective flight operations.