Which phenomenon most clearly extended the founding principles of liberty
and egalitarianism?

A. Westward territorial expansion

B. The assimilation of American Indians

C. The campaign for women's suffrage

D. Immigrant quotas and restrictions

The founding principles of liberty and egalitarianism most clearly extended by the assimilation of American Indians.

Option: B

Explanation:

Egalitarianism or equalitarianism emphasize the equality of people in respect of fundamental right and moral status.

This doctrine promotes the phenomena that all public should be treated equally in respect of social, political, economic and civil rights.

Liberty promotes the reformation of civic norms, promotion of democratic society, equal protection of laws, favorable condition for individuals to acheive their civil rights.  

Assimilation of American and Indian and formation of Anglo-American society is the result of egalitarianism and liberty.

might be agreeing to participate ethically with other european nations in the slave trade

or notifying other european nations when taking possession   of african territories

d. hip hop

it was originated in the 70s while the harlem renaissance occured in the 1920s