D is the answer to this question. If in case you are wondering what is the main difference between a routable and a non-routable IP address, it is how easy they would be to view. The routable IP address can obviously be viewed easily because it is visible. The non-routable IP address, on the other hand, cannot be seen.
The non-routable IP addresses are the ones that we may have at home or in the office. This makes the network more private because only a select group of people will be able to enter the non-routable IP address. The routable IP address is more visible and can be accessed by almost everyone publicly.