In the 1840s, the term manifest destiny was used by many americans to justify
(1) the extension of slavery into the territories
(2) war with russia over the oregon territory
(3) the acquisition of colonies in latin america
(4) westward expansion into lands claimed by other nations

(4) westward expansion into lands claimed by other nations.

Explanation:

Manifest Destiny was a doctrine that argued that the United States had a divine right to settle the entire continent of North America. Proponents of this doctrine believed that the United States had been chosen to colonize the whole region because of its unique and advances characteristics, such as its rule of law, its industry, its religious values or its legal system. This idea was used to justify the imperialism that the United States engaged in during the 19th century.

it would be

populist movement, in u.s. history, politically oriented coalition of agrarian reformers in the middle west and south that advocated a wide range of economic and political legislation in the late 19th century. thus in 1892 their leaders organized the populist, or people's, party, and the farmers' alliances melted away.