World War 1 1914-1918

1.What caused WWI?
2.Why did the U. S. enter WWI?

no options provided, here,but the answer to this question is often: a historian cites a japanese newspaper article published a year after the end of world war ii in order to draw conclusions about the effect of the war on the japanese economy.

clearly from the answer, the historian alludes to historical sources,and records to aid in analyzing and drawing conclusion on the effect of the war on the economy of japan.

hello there, can you add the "following" multiple choices