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The correct answer is letter D. The French Revolution and the instability that followed it.
Step-by-step explanation:
The French Revolution was a social and political conflict that teared down France and ended with the putsch of Napoleon Bonaparte at the end of XVIII century. As a consequence, Auguste Comte, a French philosopher who established the basis of positivism. This results from the epistemology that he created and extends to Europe in the second half of XIX century. The need to study scientifically the human being was born due to the stitches of French Revolution, which forced to see society and individuals as objects.
Comte as well introduced the term of "sociology" which defines that society needs to be guided by thinkers who understand social laws.