Answer:
D. Site-to-site VPN
Explanation:
This type of network basically allows multiple offices in different locations to establish secure connections with each other over a public network such as the Internet. A Site-to-site VPN allows computers from one location to share resources with the rest inside the network. An example of a company that would use this connection, is a growing corporation that has a lot of offices around the world.
The advantage against a remote VPN connection, is that you don't need to install a VPN client software in each terminal connected to the network.