In the 18th and 19th centuries, why did european countries practice imperialism?
a. they hoped to develop their economies to compete with east asia.
b. they were in competition with one another for resources in africa.
c. they believed it was their duty to spread islam to the world.
d. they were engaged in longstanding proxy wars in central america.

The answer is B, they were in competition with one another for the resources in Africa, which is why they practiced imperialism.

Imperialism represented a way for European countries to expand their empire and exploit the resources in the countries they conquered. In the 18th and 19th centuries, great empires like the Spanish, the British and the Portugese were in a battle to gain as much territory in America, Africa and Asia as possible.

congress also has implied powers, which derive from the necessary and proper clause of the constitution and permit congress "to make all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this constitution in the government of the united states.

c. is the western hemisphere.