|A||Full source and destination address|
|B||A short VC number|
|C||Only source address|
|D||Only destination address|
The correct answer is :B
The answer is explaining what a short VC number, also known as a VCID (virtual circuit identifier), is and how it is used in a connection-oriented circuit-switched network.
In a network that uses virtual circuits, a short VC number is used to differentiate between multiple virtual circuits that are established within the larger packet-switched network. Each virtual circuit represents a specific communication path used for transferring data between two endpoints in the network. The VCID is used as a unique identifier for each virtual circuit, allowing the network to keep track of them and ensure that data is sent to the correct destination.
See more: https://192-168-i-i.com/a-4-byte-ip-address-consists-of/