The correct answer is: popularized the idea of the United States as a melting pot of ethnicities.
Explanation: Is a series of letters written by Hector St. John Crèvecoeur.
He talks about the American people, about how society behaves. About Americans as an ideal society. It speaks of discipline and the work of the people.
Shows a national and proud side of the American people was their most well received, and most influential work.