Answer: C. the introductory paragraph
Explanation: A thesis is a theory or an idea that the author expresses as a statement and then discussed it using logical arguments. When structuring an argument the thesis is the most important element because it expresses our point of view about the subject, and also represents the statement that must be refuted or approved, so, it must be in the introductory paragraph because it is the base of the following arguments we are going to write.
It looks to be both A and B but if you can only choose one I would go with B. Hope I helped!
