Answer: d. It is physically separate from the rest of the United Kingdom, a multinational state.
Explanation:
Northern Island is one of the constituent countries of the United Kingdom and from the map one can see that it is physically separated from the rest of the U.K. .
The entire island where the Irish countries are situated used to be part of the U.K. up until 1922 when the current Republic of Ireland seceded from the U.K. after the Irish War of Independence.
