Hello. You did not present the excerpt to which this question refers, which makes it impossible for it to be answered. However, I will try to help you as much as possible.
It is only possible to determine the central theme of an excerpt, after reading it. In that case, the first step in answering that question is to read the entire excerpt. After that, you will be able to identify the central theme, since that theme refers to the message that the author wants to pass on to the reader with the reading. In that case, you can find the theme of the excerpt by asking the following questions: "What does this excerpt talk about?", "What message can I understand from this excerpt?", "Is there a lesson being taught in this excerpt? is this lesson?".
