Answer:
B) railroad industry.
Explanation:
The railroad industry declined during the 1920s. The railroad industry was one of the most profitable businesses of the late 19th century. Moreover, it had connected the country and allowed settlement to take place in remote areas. However, by the 1920s, the industry was a lot less profitable. One of the main reasons for this was the fact that the automobile was becoming more popular, as well as more affordable, reducing the need for railroads.
