2. which of the following has been mentioned by historians as a cause of world war i?

The wording of this question is a little confusing, because I don't really know what you're asking for.

There have been several events cited as contributing factors to the cause of the first world war, I like to use a little word to help me remember:

ANIMAL

A - Awful Governments:
N - Nationalism
I - Imperialism
M - Militarism
A - Alliances
L - List of events:

- German Naval Wars
- Morrocan Crisises
- Bosnian Crisis
- Agadir Crisis
- Balkan Wars
- Fall of the Ottoman Empire
- 1905 Kaiser Whilhelm Dailty Telegraph Interview
- Assassination of Arch Duke France Ferdinand
- Serbia's annexation of Bosnia

And this too use this if needed