The main cause of the second industrial revolution was, natural resources, abundant labor supply, strong government policy and new sources of power.
B. The actual number of farmers increased between 1840 and 1900.
The event that ultimately led to World War I was the assassination of Franz Ferdinand and this led to war across Europe.
<h3>What is World War I?</h3>
Your information is incomplete as the options aren't given. Therefore, an overview will be given.
It should be noted that World War I simply means the first world war that occured between 1914 and 1918. The event that ultimately led to World War I was the assassination of Franz Ferdinand.
Learn more about World War I on:
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