The correct answer is A) Germany.
The nation that the Allies thought posed the most serious long-term threat was Germany.
The allies were the alliance formed by Great Britain, the United States, France, and the Soviet Union during World War II. They fought the Axis Powers of Germany, Italy, and Japan. The allies always thought that Germany was the biggest threat to the stability of Europe in that Hitler had developed a powerful army with modern weaponry in the Navy, Army, and Air Force. They also thought that Hitler's ambition had no limit. That is why the combination made Germany a real long-term threat.