What does George Washington say makes Americans into “one people”?

The letter was first published as The Address of Gen. Washington to the People of America on His Declining the Presidency of the United States in the American Daily Advertiser on September 19, 1796, about ten weeks before the presidential electors cast their votes in the 1796 election. It is a classic statement of republicanism, warning Americans of the political dangers which they must avoid if they are to remain true to their values. It was almost immediately reprinted in newspapers throughout the country, and later in pamphlet form.[2]

The first draft was originally prepared by James Madison in June 1792, as Washington contemplated retiring at the end of his first term in office.[3] However, he set it aside and ran for a second term because of heated disputes between Secretary of the Treasury Alexander Hamilton and Secretary of State Thomas Jefferson which convinced Washington that the growing tensions would rip apart the country without his leadership. This included the state of foreign affairs, and divisions between the newly formed Federalist and Democratic-Republican parties.[4]

As his second term came to a close four years later, Washington prepared a revision of the original letter with the help of Hamilton to write a new farewell address to announce his intention to decline a third term in office. He reflects on the emerging issues of the American political landscape in 1796, expresses his support for the government eight years after the adoption of the Constitution, defends his administration's record and gives valedictory advice to the American people.[5]

hope this one helps..

The answer is option c.