Which term means a policy in which a country extends its power and authority over foreign countries and colonies?
A. dictatorship
B. imperialism
C. socialism
D. cornerism

Imperialism

Explanation:

president thomas jefferson commissioned the expedition shortly after the louisiana purchase in 1803 to explore and to map the newly acquired territory, to find a practical route across the western half of the continent, and to establish an american presence in this territory before britain and other european powers

the answer is b. hope this !