You are given a short paragraph, a question and two choices to answer from. Choose the correct answer based on the paragraph and write the answer(not the key).
Q: Paragraph: Because richer nations use more fossil fuels, they also cause more air pollution and global warming than poorer nations do.
 Question: Chris is studying two countries. He finds that China has half as many factories putting out fossil fuels into the air than the United States. Based on this information, the factories in _____ are causing more air pollution. 
 Choices: A)United States 
B)China
A:
United States