The correct answer is C) Europe First.
The two-front Allied strategy used to defeat Hitler was Europe first.
In the overall strategy of the Allied Forces to defeat Hitler and Germany, “Europe First” or “Germany First”, was the most important for Great Britain and the United States. Most of their resources would be focused on defeating the Germans in Europe territory. And just a portion of their resources would be dedicated to combat and defeat Japan in the Pacific.
The other options of the question were, a) Wolf Pack strategy, b) Block-by-Block strategy, and d) Arsenal of Democracy strategy.