Final answer:
c) Westward Expansion.
Manifest Destiny, the Dawes Act, and the transcontinental railroad are associated with the Westward Expansion characterized by the cultural belief of destined territorial growth, legislation impacting Native Americans, and technological developments linking the country.
Step-by-step explanation:
A belief in manifest destiny, the passage of the Dawes Act, and the completion of the transcontinental railroad are most closely associated with c) Westward Expansion.
During the Westward Expansion movement of the 1840s, Manifest Destiny emerged as a cultural and religious rationalization for American territorial growth, implying that the U.S. was preordained to expand its democratic institutions 'from sea to shining sea.'
The Dawes Act was a significant legislative measure enacted to encourage and formalize the division of tribal lands into individual plots as part of this expansion, which had the consequence of dismantling tribal sovereignty and assimilating Native Americans into Euro-American culture.
Completing the puzzle of national connectivity, the transcontinental railroad was one of the technical achievements that fueled industrial growth and facilitated the economic exploitation of the Western territories, naturally intertwining with Manifest Destiny's push for expansion.