Why did the u. s. avoid involvement in wwii until december 1941? why was the pearl harbor attack such a shock to the u. s? america the story of us?

By the late 1930s, how were u. s. officials beginning to view japanese policies of expansion? a. they attempted to join forces with japan so as to increase u. s. territory. b. they warned them to stop expansionist actions or face potential u. s. intervention. c. they sent representatives to japan to work out territorial rights in a diplomatic fashion. d. they became fearful of their military power