Which of the following most accurately explains the emergence of a large American middle class after World War 2?
A. Women became an increasingly important part of the workforce, greatly increasing their buying power.
B. The expansion of the railroad industry and improved communication capabilities created a national market for goods.
C. The U.S. economy shifted from wartime production to the peacetime manufacture of consumer products.
D. The size of the average family fell rapidly, allowing individuals to spend more money on themselves.