Which of the following best describes the relationship between the countries of the Allied Powers?

A
Serbia, Japan and Romania were the Allied Powers who fought against one another.

B
The Allied Powers of France, Britain and Russia agreed to help each other fight if one of them was attacked.

C
The Allied Powers of Austria-Hungary and Greece fought together against the Ottoman Empire.

D
Germany, Austria-Hungary and Italy were the Allied Powers who agreed to help each other fight if one of them was attacked.