Concept:Poste restante is a postal service in which letters and parcels are kept at a named post office until the receiver comes to collect them.
Explanation:A tourist may be moving from place to place and not have a permanent residence.
Without a home address, receiving letters through normal delivery is difficult.
Poste restante provides a simple solution by allowing mail to be sent to a particular post office.
The tourist then visits that post office, identifies himself or herself, and collects the mail.
This service is especially helpful for travellers, new arrivals, and people staying in an area temporarily.
The other options do not fit this situation.
Parcel post is simply a delivery method for packages.
A private mail bag is usually arranged for businesses or institutions, not for transient tourists.
Recorded delivery is a way of obtaining proof of delivery for an item, not a method of receiving letters without an address.
Therefore, the correct option is poste restante.
Answer:A. poste restante