I will give 5 points, a thank you, a 5 star, and a brainliest if correct.

In the mid-1800s, Democrats believed that a policy of Manifest Destiny

A. would prevent a war with nations that claimed territory in North America.

B. was less important than developing existing territory in the United States.

C. would boost the American economy and open up economic opportunities.

D. would prevent hostilities with American Indian tribes that lived in the West.