Explain how it is possible for a sequence of packets transmitted through a wide area network to arrive at their destination in an order that differs from that in which they were sent. Why can’t this happen in a local network?

What will be an ideal response?

Packets transmitted through a store-and-forward network travels by a route that is determined dynamically for each packet. Some routes will have more hops or slower switches than others. Thus packets may overtake each other. Connection-oriented protocols such as TCP overcome this by adding sequence numbers to the packets and re-ordering them at the receiving host.
It can’t happen in local networks because the medium provides only a single channel connecting all of the hosts on the network. Packets are therefore transmitted and received in strict sequence.