Final answer:
Germany being directly blamed for the start of World War I is best demonstrated by the assassination of Archduke Ferdinand.
Step-by-step explanation:
The best demonstration of Germany being directly blamed for the start of World War I is option C) Assassination of Archduke Ferdinand - Sparked the conflict. The assassination of Archduke Franz Ferdinand of Austria-Hungary by a young Serbian nationalist was the immediate cause of the war. This event led to a chain reaction of alliances and declarations of war.