Welcome to your interview.
The question is on your right: Vectorization vs Loops in Pandas. 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 vectorization and iterative loops in Pandas, and why one is preferred for large-scale data manipulation.