Configuration settings of an application are typically set once and do not change while the application is running. The use of a constant is appropriate in this case because constants are meant to store data that remains the same throughout the execution of the program. Although environment variables could seem like a tempting answer since they can hold configuration settings as well, they are not ideal in this case as they are mutable and can introduce risks if changed at runtime. Literal strings and user input variables are incorrect choices because they pertain to different contexts; literal strings represent fixed string data, and user input variables are intended for data that is expected to change as it relies on the user's interaction.