Question

What best explains why the Central Powers were unable to defeat the Allied Powers once Russia was out of the war?

The Austro-Hungarian empire surrendered to the Allied Powers.
Italy joined the Allied Powers and opened up a new front in the east.
The Arabs defeated the Ottomans and advanced north into Austria-Hungary.
O The United States entered the war on the side of the Allies.

Answer 1

The United States entered the war on the side of the Allies.

I don't know for sure but I think its that one because I learned this last year.