Welcome to your interview.
The question is on your right: Correlation vs Causation. 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.
What is the difference between correlation and causation, and how do you control for confounding variables in an observational study?