Welcome to your interview.
The question is on your right: Market-Making Bid-Ask Spread. 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.
Make a market on the number of gas stations in the state of Pennsylvania. What is your bid-ask spread?