Which of the following expressions can indicate a conclusion?

The expression "In short" serves to summarize or restate the main points of an argument or discussion concisely, making it a strong indicator of a conclusion. This phrase often appears at the end of a discussion to encapsulate the key takeaways, reinforcing the overall message or findings presented previously. When you encounter "In short," it typically signals to the reader that a conclusion is being drawn from the information that has been provided.

The other expressions serve different functions: "Additionally" introduces more information, "First of all" signifies the beginning of a list or sequence, and "Overall" may offer a general statement but does not necessarily draw a conclusive statement as directly as "In short" does. This distinction clarifies why "In short" is the most appropriate choice for indicating a conclusion.