Question

which is the correct order of events that occurred after austria - hungary declared war on serbia?
russia mobilized its forces, prompting germany to declare a two - front war against russia and france.
france mobilized its forces, prompting germany to declare a two - front war against france and russia.
germany mobilized its forces, prompting russia and france to declare war against germany and austria - hungary.
austria - hungary mobilized its forces, prompting russia and germany to declare war against austria - hungary and france.

Explanation:

After Austria - Hungary declared war on Serbia, Russia mobilized its forces in support of Serbia. This mobilization by Russia prompted Germany to declare a two - front war against Russia and France as part of its military strategy (the Schlieffen Plan). France had an alliance with Russia and was a target in Germany's plan to quickly defeat France in the west before turning to face Russia in the east.

Answer:

Russia mobilized its forces, prompting Germany to declare a two - front war against Russia and France.