Answer:
I believe it is B but if you have a text you can see if the answer matches with the text
It left the entire west in ruins, basically the reason for feudalism and the Dark Age
Explanation is in the file
tinyurl.com/wtjfavyw
Serbia supplied the rebels with weapons so that they could kill the archduke. Austria-Hungary declared war on Serbia. Russia entered to defend Serbia because they both had large Slavic populations. Germany entered to defend Austria-Hungary. Alliances drew other countries in until it was a world war.
