Welcome to your interview.
The question is on your right: GROUP BY vs PARTITION BY. 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.
Explain the difference between GROUP BY and PARTITION BY in SQL, and when you would use each.