There were millions of people who moved into New York City in the late 1800s. How could millions of people live and work in such a tight space?
a. The city built skyscrapers and the Brooklyn Bridge allowed people to live outside Manhattan
b. People could only hold jobs for a certain amount of time before they had to move
c. They started to make homes and factories underground
d. There was a limit on how many children each family could have to control population