Ralph Waldo Emerson against the acquisition of the Southwest following the Mexican-American War. Option four is correct.
Ralph Waldo Emerson was an American essayist, lecturer, philosopher, and poet, head of the transcendentalist movement of the mid-19th century.
He moved away from the religious and social beliefs of his contemporaries, developing and conveying the philosophy of transcendentalism in his 1836 essay "Nature".