Why did the Allies exclude Russia from the peace talks in Versailles?

A.
They had sided with the Axis powers at the end of the war.

B.
They had refused to join and negotiated their own treaty instead.

C.
The new communist regime had already signed its own peace treaty.

D.
Russia was still technically at war with the Ottoman Empire in Crimea.

The correct answer is B. Russia had refused to join the peace talks in Versailles and negotiated its own treaty, the Treaty of Brest-Litovsk, with Germany in 1918. The Allies were unhappy with this separate peace agreement and felt that Russia had abandoned the war effort. Additionally, the new communist regime in Russia was seen as a threat to the capitalist governments of the Allies. Therefore, they excluded Russia from the peace talks in Versailles.