Welcome to your interview.
The question is on your right: Investigate Low Conversion. 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.
If Mars store foot traffic is high but conversion rates are low, what metrics would you investigate first, and why?