Which of the following statements best describes environmental changes caused by westward railroad expansion? Western forests were cut down for lumber for railroad and bridge construction. Western factories were built in what had been wooded rural areas. Changes occurred only in the Western plains, where animal populations decreased. The railroad expansion caused no environmental changes in the West.

Answer: a

The correct answer is option A. "Western forests were cut down for lumber for railroad and bridge construction". Westward railroad expansion was an example of urban development, that took place from 1863 to 1869 communicating towns and cities in the old west. However, the construction of the railroads and bridges impacted the environment as Western forests were cut down to gather lumber for construction.