Rosa Parks is famous for her actions during the Civil Rights movement. Although she initially dropped out of high school, she returned later to earn her high school diploma when she was around 20. Not many people in Montgomery, Alabama, finished school at that time. She got a job at Maxwell Field, an Air Force base near her home, thanks to her diploma. When Rosa worked on the military base, President Roosevelt decided that military bases could not be segregated. This meant workers of different races could be together, but that wasn't how it was outside the base. Segregation laws separated people of other races in all public places. So, on the bus Rosa had to take home, she had to ride in the back.

Which of the following details helps explain segregation?