Question

which event had the immediate effect of causing germany to declare war on the allies?
the berlin conference of 1885 sets off the scramble for africa.
russia mobilizes its forces on germanys eastern borders.
great britain declares war on germany.
the austrian archduke is assassinated.

Explanation:

• The Berlin Conference of 1885 was about the division of Africa and not related to Germany declaring war on the Allies.
• When Russia mobilized its forces on Germany's eastern borders, Germany, fearing a two - front war (with Russia in the east and France in the west, as per its war plans), declared war on Russia (an Allied power at the time).
• Great Britain declaring war on Germany was a result of Germany's actions (like invading Belgium) rather than the cause of Germany declaring war on the Allies.
• The assassination of the Austrian archduke was the long - term trigger for the start of World War I but not the immediate cause of Germany declaring war on the Allies.

Answer:

Russia mobilizes its forces on Germany’s eastern borders.