What essential information must be briefed to a passenger traveling with an infant in lap?

When briefing a passenger traveling with an infant in lap, it is crucial to communicate the location and operation of the infant life vest. This information is vital for safety, as it prepares the passenger for potential emergency situations. An infant life vest is specifically designed for infants and toddlers, and knowing how to correctly deploy and use it can make a significant difference in ensuring the safety of the child should an emergency arise.

The other options, while they may enhance the passenger's comfort or experience during the flight, do not directly pertain to the immediate safety and security of the infant in the event of an emergency. Providing information about the restroom location or the onboard entertainment system is helpful for convenience but does not equip the passenger with critical safety knowledge. Likewise, rules for exiting the aircraft are relevant but not specific to the safety of an infant.