Answer: Site to site VPN
Step-by-step explanation:
A site to site VPN is the connection in which it allow offices to establish a secure connection over they public network like internet. It can easily connect multiple network in the office like it connect the various remote office with the company headquarter for communication.
The site to site VPN network is very secure as compared to traditional VPN system. All the traffic are get encrypt in the tunnel from one site to the another site.
And all the other options are not much efficient as they does not provide any high effective VPN system as compared to site to site VPN system.
Therefore, correct option is Site-to-site VPN.