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.
The correct answer to the given question above is the content of "What Exactly Are Green House Gases". The author in the story "An Inconvenient Truth" uses the content of "What Exactly Are Green House Gases" to emphasize how humans can improve the atmosphere.