Which sentence in Kristin's introduction requires revision for formal tone?

The sentence that requires revision for formal tone is the one that begins with "In this essay, I will explain..." This sentence introduces the content and structure of the essay in a conversational manner, which is more characteristic of informal writing. In formal writing, particularly in academic contexts, it's generally more effective to state the purpose of the essay without using first-person phrases such as "I will." Instead, it would be more appropriate to present the thesis directly, focusing on the arguments or analysis to be presented, without overtly referencing the writer's intentions. This shift creates a more objective tone, aligning with academic standards and enhancing the overall formality of the essay.

This adjustment not only maintains a professional tone but also invites the reader to engage with the ideas rather than the author's perspective. The other sentences in Kristin's introduction maintain a more formal and analytical approach, appropriate for academic writing, which supports the idea that the third sentence is the one needing revision.