"An internal system behind a firewall needs to be configured for remote access. How should Network Address Translation be configured?"

The appropriate answer will be "Port forwarding ".

Explanation:

Port forwarding seems to be a network security strategy whereby a gateway or equivalent system communicates all intercepting communication/traffic from a specific address to some of the same port on just about any interior single node.This allows the connection of an entity in this context device that is connected to an inner reference node/port usually connecting to Internet infrastructure as well as an internal private local area network.