Answer:
B. The growth of the railroads increased the demand for natural resources.
Explanation:
Railroad transportation changed the way American people traded. For instance, agriculture products were transported easily throughout the country.
Didn't read the book but mostly Louis was brave because he risked making vaccines and testing them on others to save many more people. He made the effort to save others and did a lot of work and experiments to help advance the medical world of science.
Over the period of the Atlantic Slave Trade, from approximately 1526 to 1867, some 12.5 million slaves were shipped from Africa, and 10.7 million arrived in the Americas.
