Which of the events that you listed was most influential in bringing the united states into the war?

Which war?   

WWI = loans, unrestricted warfare, Zimmerman note, Germany attacking a neutral country (Belgium).  

WWII  = loans, Pearl Harbor.  

Do you have more info about it ? i doubt this is the answer because i don't have all the information but if trouble was brewing in a clinic maybe it was an argument as to which clinic was better or smth of that nature