To return the string 'Hello! We're ready' in SQL, we need to use methods that properly handle special characters like the single quote. Using the `q` syntax in Oracle SQL allows us to define alternative quoting mechanisms, making it easier to include single quotes in the string. The queries `SELECT q'!Hello! We're ready!' FROM DUAL;` and `SELECT q'[Hello! We're ready]' FROM DUAL;` both correctly handle the single quote within the string, ensuring the query executes without errors and returns the desired string. Other options either contain incorrect syntax or will not execute properly due to the way they handle the special characters.