Explain the importance of the Cotton Gin and the Railroad on the south.

While it was true that the cotton gin reduced the labor of removing seeds, it did not reduce the need for slaves to grow and pick the cotton. ... Cotton growing became so profitable for the planters that it greatly increased their demand for both land and slave labor.

D is the correct answer.

The Pentagon Papers were leaked by Daniel Ellsberg in the New York Times in 1971 and showed that the United States Government, specifically the Johnson administration, systemically lied about the scope and effectiveness of American involvement in Vietnam.