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  The First World War was a worldwide conflict which began with the declaration of war by Austria-Hungary on Serbia on the 28th of July, 1914. The event leading to this was the assassination of Archduke Franz Ferdinand, the presumptive heir of the Austro-Hungarian Empire, by a Bosnian Serb.

Explanation:

answer; i believe the answer is 80%, plz check first good luck;

  b.

there are isolated pockets of farming, generally around rivers and oases, which are used for irrigation.