The answer is B.the United States emerged as one of the world's most powerful Nations .
Let's look into it one by one:
A. the United States can a global Empire taken from Germany - This is false.
The United States never form a global empire. In fact, after World War I, there was a decline if empire and all the empire collasped turning into republic or governed under communist or totalitarian parties.
B. the United States emerged as one of the world's most powerful Nations - This is correct.
After WWI,many nations are weakened significantly, suffering from the casualties of war, destruction of infrastructure and the was burdened by the cost of war. Many nations were in economic dilemma, while America rose steadily with well-developed economics
It was the nation that lend loans to many countries, also leading in scientific development with steady politics. Thus we can see it's position is significant,emerging as one of the most powerful nations.
C. the United States was weakened by the devastation of the war- This is not true.
Though spent quite an amount on war, the cost barely affect economy, not to mention it joined in the war late thus suffered the least casualties.
D. the United States became a leading member of the League of Nations- This is incorrect as well.
Although it was The Us president, Woodrow Wilson who suggested the formation of League of Nation, US herself did not participate as one of the members.
Hope it helps!