What caused nations to assert imperial dominance on imperialized regions?

Imperialism is a policy or ideology of extending the rule over peoples and other countries, for extending political and economic access, power and control, through employing hard power especially military force, but also soft power. While related to the concepts of colonialism and empire, imperialism is a distinct concept that can apply to other forms of expansion and many forms of government.

Expansionism and centralization have existed throughout recorded history by states, with the earliest examples dating back to the mid-third millennium BC. However, the concept of imperialism arose in the modern age, associated chiefly with the European colonial powers of the 17th, 18th, and 19th centuries and New Imperialism. Following the decolonization of European holdings, the concept has further evolved and has been broadly used to identify as well as criticism a range of policies and a number of states, including even supposedly anti-imperialist states.

d) iowa i believe is the answer

confederacy: supported slavery, believed states should be able to nullify federal laws, supported low tariffs

union: everything else