Hello. Unfortunately you did not enter the text this question refers to and it is not possible to find it by the section title. This makes it impossible for your question to be answered accurately. However, I will try to help you as best I can.
The tone of a text is the feeling the author wants the reader to feel while reading. In this case, to answer this question, you will need to read the entire text and identify the tone it presents. This tone is modified by the sentence "For a lot of reasons, Chicago checked a lot of boxes for us," as the question indicates. Thus, the feeling expressed by the text is modified and you must identify this modification, that is, you must inform what was the old feeling and what is the new feeling, presented by this sentence.
Next, you need to identify what this sentence adds to the text, that is, why it was added to the text, what meaning it carries.
You must also present how this sentence is supported in the text. This means that you should look for other sentences that show that Chicago actually checked the boxes, that is, you should look for sentences that prove this happened.
