Welcome to your interview.
The question is on your right: Diagnose a 10% Metric Drop. 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 a key business metric suddenly dropped by 10% week-over-week at Santander, how would you diagnose the root cause?