The best and most correct answer among the choices provided by the question is the third choice "The Allies wanted to ensure that Germany did not continue to conquer European territory."
Europe first, also known as Germany first, was the key element of the grand strategy agreed upon by the United States and the United Kingdom during World War II. According to this policy, the United States and the United Kingdom would use the preponderance of their resources to subdue Nazi Germany in Europe first.
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