Welcome to your interview.
The question is on your right: Open Exchange vs PMP Positioning. 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.
Can you explain the difference between open exchange and private marketplace (PMP) deals, and how you would position a PMP to a major brand?