Industrial Enterprises Grew to Unprecedented Sizes in the Late Nineteenth

Industrial enterprises grew to unprecedented sizes in the late nineteenth and early twentieth centuries, partly because __________.

A) markets were being closed all over the world
B) new technologies required huge levels of investment and manpower
C) the American economy became isolated and primarily domestic
D) the government required new enterprises to have at least a hundred employees
E) the population began to leave the cities to live in rural areas