An underlying cause of world war i was
a. the ongoing dispute over the convoy system.
b. the web of alliances european nations created for their defense.
c. an alliance between the autocratic rulers of germany and russia.
d. american insistence on neutrality.

An underyling cause of World War I was that B - The web of alliances between the different European nations created for their defense - European nations or rather thier kings were already making strategic partnerships and alliances for a long time since that time to ensure their survival in the long run.