The best answer choice would be A.
their disagreement was over who the successor was
This can be something as bizarre as an Alien from another Galaxy, or whether or not you should get paid. This question is very general and usually should be answered where the opposition or question is not in America or American, as that will ruin the unite everyone.
The two groups that fought each other in World War I became known as the Triple Alliance (the main forces were Germany, Austria-Hungary, the Ottoman Empire and Italy) and the Triple Entente (the main forces were Russia, Great Britain and France)
