The correct answer is "Great Britain".
The German attack on RMS Lusitania and sinking of the same ship by a submarine caused Americans to join the war. This is just simply put of course, there were many other reasons.
Generally speaking, in a "unitary system" the <span>government is completely controlled by the national government, since this means that there is only a single control group, as opposed to a republic, where power is often shared between entities. </span>
The alliances system meant that a local conflict could easily result into an intimidating global one. The overall cause of World War was the assassination of Archduke Franz Ferdinand. Nationalism was a great cause of World War one because of countries being greedy and not negotiating.
Your welcome I don't know if that helped. But yea.
Answer:
Agriculture caused human to form advanced societies and trade economies
Explanation: Humans no longer had to find and hunt food, they could grow their own and trade to others for goods and services while remaining staionary
