This common technique, employed at the edge of a network, eliminates the need for public IP addresses on a private network while hiding the actual addresses of internal network hosts.

a. firewall b. NAT c. DHCP d. DMZ

NAT

Explanation:

Network Address Translation (NAT) allows nonroutable IP prefixes to hide behind a routable address.it translates IP addresses and ports of its internal hosts, hiding the true endpoint of an internal host on a private network.

Using NAT in this way allows network engineers to efficiently route internal network traffic to the same resources, and allow access to more ports, while restricting access at the firewall.

i think the answer is b.