19) which of these was a factor in the united states entrance in world war i?

Germany's Unrestricted subamrine Warfare

Explanation:

the hyksos invasion. the hyksos were able to attack egypt successfully because of their skills in using bronze weapons, composite bows and the use of the horse and chariot during the invasion. although the egyptians depict a barbarian-type overthrow, the truth is the seizure was likely a relatively peaceful one.