Welcome to your interview.
The question is on your right: A/B Test for Recommendation Feature. Take a moment with it first.
Talk your thinking through with me if you like - when you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes). Discussion and graded submissions share your five interviewer interactions, so spend them well.
Design an A/B test to evaluate a new recommendation feature, including the primary metric, guardrail metrics, sample size, and stopping rules.