Your question is Mitigate Web XSS. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
How would you mitigate a Cross-Site Scripting (XSS) vulnerability in a web application? Explain how you would identify the injection context, prevent stored, reflected, and DOM-based XSS, and verify the fix. Include relevant browser controls, secure coding practices, testing, monitoring, and incident response steps.