Answer: d. concentrate first on the war in Europe and to place the Pacific war against Japan on the back burner.
Explanation:
Neither the British nor Roosevelt saw Japan as a serious long term threat. Because of this, they decided that it would make more sense to first defeat Hitler and Germany who they considered far superior opponents than the Japanese then bring their might down on the Japanese who they felt would not be as hard to defeat.
In order not to be totally absent from the Pacific Theatre against Japan though, they still fought a 'holding' action against Japan by using fewer resources.