Rose read the following passage: During the Dust Bowl, many farmers lost their harvests and had to find new ways of making money. Men and women traveled across the United States in search of work. Many of these traveling workers became known as hobos, a famous group of people during the Great Depression era. They rode on trains in search of jobs. Whenever they found work, they sent money home to their families. They hoped that, if they could raise enough money to keep their farms, they would be able to resume planting crops once the Dust Bowl ended.

Which background knowledge would best add to Rose’s understanding of the passage?

knowing what the Dust Bowl was, including its causes and effects
knowing how much money the hobos sent home to their families
knowing how the Dust Bowl compares to droughts in other countries
knowing why the hobos favored trains for transportation between jobs