Welcome to your interview.
The question is on your right: ROI in Illiquid Commodity Markets. 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.
Walk me through how you would measure the return on investment (ROI) of a marketing campaign in a highly illiquid or niche commodity market.