(A) Germany attacking France
(B) ** the assassination of Archduke Franz Ferdinand
(C) the sinking of the Lusitania
(D) the Zimmerman telegram
EXPLANATIONS BELOW
Concept note-1: -The assassination of Archduke Franz Ferdinand was the immediate cause of a war between two great powers-Russia and the Habsburg Austro-Hungarian Empire.
Concept note-2: -The assassination set off a rapid chain of events, as Austria-Hungary immediately blamed the Serbian government for the attack. As large and powerful Russia supported Serbia, Austria asked for assurances that Germany would step in on its side against Russia and its allies, including France and possibly Great Britain.
Concept note-3: -Immediate Cause: Assassination of Archduke Franz Ferdinand The immediate cause of World War I that made all the aforementioned items come into play (alliances, imperialism, militarism, nationalism) was the assassination of Archduke Franz Ferdinand of Austria-Hungary.