Question

What did the Treaty of Brest-Litvosk accomplish in the war?

Answer 1

The best option from the list would be that the Treaty of Brest-Litvosk "ended Russia's involvement in World War I", since the Russians were going through a Civil War. 

Answer 2

The answer is: It ended Russia's involvement.

The treaty of Brest-Litovsk was signed on March of 1918, after months of negotiations, between the Central Powers (Germany, the Ottoman Empire, Austria-Hungary, and Bulgaria) and Russia in the context of World War I, and which effectively ended Russia´s participation in the war and stopped further invasions. Russia, at the time, was fighting its own civil war and this treaty brought certain stability to the Bolsheviks leading their civil war.