Descartes uses the 'evil genius' to extend radical doubt to all aspects of experience, questioning the certainty of knowledge. This philosophical method ultimately leads him to the undeniable truth of his existence as a thinking being. Thus, the chosen answer is A: extend radical doubt to all aspects of experience.
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Descartes uses the concept of an 'evil genius' to extend radical doubt across all aspects of knowledge, questioning the certainty of our perceptions and beliefs. This thought experiment ultimately leads him to find an undeniable truth: the certainty of one's own existence as a thinking being. Thus, the evil genius serves as a philosophical method rather than a tool for intimidation or deception. ;