That his boss was a communist
Since Russia had an alliance with Serbia, it ordered its forces to mobilize for war. it wasn't a formal alliance, but it did specify that if someone declared war on Serbia, Russia would also step in. This resulted in other countries also getting involved in the war. The answer would be D!
-TetraFish
Answer to your question, in the same order.
1.- D
2.- B
3.- B
4.- A
5.- C
6.- A
7.- A
8.- C
