Which of the following was the most important cause of World War One: Alliances, Empire, Arms race and the assassination?

There is no
objective way to determine which of these factors was the most important in bringing about the
start of .  All of the factors had an impact and it is not possible to accurately measure each
of these impacts.  I would argue that the most important overall factor was the desire for
empire and power.  This desire caused alliances to form.  Once the alliances were formed and the
various countries were completely suspicious of one another, the assassination could ignite the
powder keg and cause the war to begin.

The most important of the factors
that you mention was the...

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