In the context of Computer Networks, which of the following best describes the…

Concept — Packet switching means a message is divided into packets that are multiplexed statistically over shared links: no capacity is dedicated to one conversation, and each packet is stored and forwarded hop by hop, competing for every outgoing link with all other traffic. The technique takes two forms. In the datagram form each packet carries a full destination address and every router decides its next hop independently, so the packets of one message need not follow a common path. In the virtual-circuit form (X.25, Frame Relay, MPLS) one path is chosen at setup and every packet of the flow is switched along it.

In neither form is delivery timing fixed, because the queueing delay at each hop depends on whatever other traffic happens to be present. Packet switching therefore guarantees neither a common path nor equal transit times; it only permits them. Higher layers repair what the network does not promise: TCP numbers the bytes it carries inside its segments, buffers whatever arrives, and hands the byte stream to the application in its original order.

Application — Sent this way, two consecutive packets of one message can be pushed onto different outgoing links at the first congested router, cross paths with different hop counts, and wait in queues of different depths. They can therefore reach the receiver separated in time, and the packet sent second can be delivered to the receiving stack before the packet sent first. The right description is consequently a permissive one — packets MAY take different routes and MAY arrive at different times in a different order — not an absolute promise about route, timing, or sequence.

Cross-check — Setting the four behaviour combinations against that concept separates them:

Result — Transmission of a message by packet switching is best described as: data packets may follow different routes and may arrive at different times in different order.