What was the plan to fight Russia in the east while the Germans attack France in the west?
O
Attack Russia along side with the Austrians.
Hold on at all cost and stop Russia from invading eastern Germany.
O
Retreat until reinforced by troops from the western front.

Hold on at all cost and stop Russia from invading eastern Germany.

Explanation:

The plan to fight Russia in the east while the Germans attacked France in the west is widely known as Schlieffen's plan.

The plan was based on many factors, among which was France was the enemy to be conquered early, with Russia contained or hold on until the French were eliminated.

Hence, in this case, the correct answer is "Hold on at all cost and stop Russia from invading eastern Germany."