Which of the following best explains why the population of U. S. urban areas increased 20 percent between 1865 and 1900? A. The federal government offered people money and housing to live in urban areas. B. Many foreign immigrants and people from rural areas moved into the cities to find jobs. C. Many people felt that it was safer to live in the city than in rural areas. D. The labor unions in many cities guaranteed jobs to people who moved to urban areas.