I believe the answer would be d. but not 100% sure
Slave labor proved profitable on plantations
Joseph Pulitzer was a Robber Baron because he used his wealth in a way that only benefited him, and had no regard for the people who were negatively affected by his actions.
People who supported imperialism claimed that it was the natural progression of civilized countries and races to expand. Expansion in a way became a matter of race. Americans were part of the great Anglo-Saxon race, which means that, like their English cousins, they were of a superior race and destined for an empire of their own.
Hopes this helps:
Answer: Industrialization helped fuel the start of imperialism in the 19th century. ... Soon, industrialization spread throughout Europe and to the United States. These new industrialized nations needed more raw materials to fuel their mass production and population growth.