What did locke meant when he wrote this passage

Nhow the other half lives, jacob riis: a. wrote about captains of industry. b. highlighted the benefits of the second industrial revolution. c. provided a fictional account of life in 1890. d. discussed the lives of wealthy americans. e. focused on the wretched conditions of new york city slums.

56: 58 the assembly line was a system through which items were mass-produced in a flow.

Why do many scientists suppose the land bridge theory of migration?