A thesis should be defined and less vague in accordance to the topic. The inappropriate thesis would be the third choice "Keitel argues that artificial sweeteners are safe, and Blackwell asserts they are not" would be the correct answer for this question because it is vague and open, where as the other example thesis are defined and direct in their word choice.
I hope this helps! Please let me know if you have any questions. :)
May 28th, 2015
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