Explanation
The correct answer is D. VPN.
A VPN (Virtual Private Network) is a service that allows a remote user to access network resources securely over the internet. A VPN creates an encrypted tunnel between the user's device and the VPN server, which acts as a gateway to the network. The user can then access the network resources as if they were directly connected to the network, without exposing their traffic to eavesdropping, interception, or censorship.
A VPN can provide remote users with access to various services on a company network, such as file and print services, client/server applications, and remote network administration1. A VPN can also protect the user's privacy and identity online by masking their IP address and location.
References:
*Remote Access to a Network - NETWORK ENCYCLOPEDIA, section "Remote access typically gives remote users access to the following services on a company network".