Why is E incorrect?

Hi @jingjingxiao11111@gmail.com Happy to help! Answer choice (E) is incorrect because the other positions that Arrian held in his lifetime are irrelevant to the conclusion of the argument. We also know that Arrian was a student of Epictetus; therefore, he learned at least some philosophy from his teacher. The argument concludes that it is unlikely that Arrian wrote The Discourses himself as the differences in views would be likely to be noticed by Epictetus' contemporaries. Therefore, it doesn't matter what Arrian's background was; we are simply focused on the fact that Arrian's views would likely be different from those of Epictetus. Hope this is helpful! Please let us know if you have any further questions.