A. France declared war on Germany immediately after Germany declared war on Russia.
B. Russia and France's military alliance was signed by leaders who are no longer in power.
C. French leaders had been planning a sneak attack against Germany since 1913.
D. Russia and France both had extremely powerful militaries during the war.
Answer: A. France declared war on Germany immediately after Germany had declared war on Russia.
Both France and Britain were allies and they declared war on Germany . This became in the time of Athenia liner which sunk in submarine of German and they assumed that the liner was belligerent and armed.
Then the Germany ships started being bombed.