Which weapon was a primary cause of the u. s. entry into world war i? a. nuclear bomb b. machine gun c. submarines d. poison gas

c.submarines

why?

Germany broke its promise to the United States to stop attacking passenger ships (unrestricted submarine warfare). German leaders knew America entering the war would increase the strength of Allied Powers.

answer: president kennedy is vowing to protect freedom in this paragraph.

social status of early civilizations was based primarily on economic power.- true ( first choice)