What is required to allow devices that are using RFC 1918 addresses to communicate over the Internet?

What is required to allow devices that are using RFC 1918 addresses to communicate over the Internet?
A. A private to public VLAN must be defined on the Internet border device.
B. The Internet firewall must permit RFC 1918 addresses.
C. VLAN translation is required on the Internet border device.
D. Network address translation is required on the Internet border device.