Final answer:
The United States' changing role in the war was from being vastly richer, larger, and more powerful to being a military superpower but lacking a strong economic power.
Step-by-step explanation:
The correct answer is B. The United States' changing role in the war changed from being vastly richer, larger, and more powerful than it had been at the start of the war (as described in the option A) to being a military superpower in the world but lacking a strong enonomic power (as described in the option E). The United States emerged from World War I as a great power, with strengthened geopolitical and economic influence.
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