What were the causes of Manifest Destiny?

The idea of Manifest Destiny arose in response to the prospect of U.S. annexation of Texas and to a dispute with Britain over the Oregon Country, which became part of the union.

Explanation:

Manifest Destiny claimed that it was the objective of the United States to absorb all of North America. Land is associated with wealth, political power and independence.

d. the right to establish a one-house legislature

i would say your answer is a)

sorry if im wrong