When did activities occur that demonstrate americans' belief in manifest destiny?

The phrase was first employed by John L. O'Sullivan in an article on the annexation of Texas published in the July-August 1845 edition of the United States Magazine and Democratic Review, which he edited. The term manifest destiny originated in the1840s.

The activities that most demonstrated Americans' belief in Manifest Destiny occurred during the 19th century, while thousands of settlers moved west and displaced thousands of natives. 

The answer is a c b d a c b d