Answer:
B. the assassination of Archduke Franz Ferdinand in Sarajevo.
Step-by-step explanation:
The Sarajevo attack is the term with which the murder is known, on June 28, 1914, of the crown heir of the Austro-Hungarian Empire, Archduke Francisco Fernando of Austria, and his wife, Duchess Sofia Chotek, in Sarajevo , capital of the imperial province of Bosnia and Herzegovina. The attack was perpetrated by Gavrilo Princip, a member of the Young Bosnia group, a movement whose objective was the emancipation of Bosnia from Austria-Hungary, which was supported by intelligence and military circles from the Kingdom of Serbia. This event was the trigger of the First World War.