Question

Island in the atlantic off the northwestern coast of mainland europe

Answer 1

Answer:

United Kingdom

Explanation:

It is possible to have two possible answers for this very short question and considering there is no more information, the landmass of the United Kingdom could be taken as the main island, which is located off the mainland of Europe.

Now it is also necessary to consider that Ireland is also another landmass which is right next to the United Kingdom and could also be seen as an island, however, in general, the United Kingdom would be the reference answer for this question.