Which type of network is implemented over a public telecommunication switching system?

The correct choice is public network because this type of network operates over a public telecommunication switching system, which means it is open for use by the general public. Public networks allow users to connect to the internet and communicate with other users from different locations without the need for private infrastructure.

In contrast, private networks are exclusive to a particular organization or group, utilizing dedicated resources that are not accessible to the general public. Virtual networks operate by using a physical network while creating logical segments within it for security and traffic management. Local area networks (LANs) are typically confined to a specific geographic area, like a building, and often require their own infrastructure. Thus, the essence of a public network is its broad accessibility, which is why it is correctly identified as the type of network that operates over public telecommunication systems.