Your question is A/B Testing and Measurement Basics. 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).
Explain how you would run A/B testing and use metrics to evaluate the results.
Cover the hypothesis, treatment and control setup, unit of randomization, primary metric, guardrail metrics, minimum detectable effect, sample-size reasoning, statistical analysis, and ship or do-not-ship criteria. Also explain how you would avoid common errors such as peeking, sample ratio mismatch, and confusing statistical significance with practical importance.