Answer:In his historic thesis, 'The Significance of the Frontier in American History,' originally presented to a group of fellow historians in Chicago, he argued that as a result of the frontier, American character and society developed differently from European or other known cultures of the time.
Explanation:
C. The Underground Railroad helped slaves escape to the North.
Answer:
Explanation:
Robert J. Oppenheimer was an American theoretical physicists. From 1939 - 1946 he was known for creating and doing research on an atomic bomb.
