The answer is D. Supply-side economics.
Answer:
Many Social Darwinists embraced laissez-faire capitalism and racism. ... The ideas of Social Darwinism pervaded many aspects of American society in the Gilded Age, including policies that affected immigration, imperialism, and public health.
Explanation:
Vanderbilt made millions by having control over two industries. the steamboat industry and the railroad industry. when he parished vanderbilt’s estate was estimated to be worth over 100 million!
B. The American victory at Saratoga convinced France to join the war on the colonists' side.