Which of the following was a cause of the increase in total U.S. urban population during the early 20th century?

job opportunities in industry
the failure of the populist movement
the success of the labor unions
improved living conditions in cities

Question

Which of the following was a cause of the increase in total U.S. urban population during the early 20th century? 
 	
	job opportunities in industry
	the failure of the populist movement
	the success of the labor unions
	improved living conditions in cities

anonymous · Answer

Most likely going to be A. The early 20th century was a transition from the more self sufficient ways of the past, to relying on other people in a more populated atmosphere. Meaning people used to live with their families out on farms. This changed due to the rise of cities, cities were areas where business was centered. 

I could be wrong, but I think it is A.

anonymous · Answer

That's what I was thinking, but I wasn't sure.

anonymous · Answer

The only one I'm sure is not right is B. Because it is irrelevant to the question. Although the rest are debatable. My APUSH mind is telling me that all are possible but A is the most probable. Success of labor unions would be possible because people would be more happy with job conditions. D is also possible because people would be more comfortable living in a city. But A is my answer.