Welcome to your interview.
The question is on your right: Implementing Singleton in Java. 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.
How would you implement a singleton pattern in Java? Walk through a correct implementation, explain how you would make it thread-safe, and mention common mistakes or edge cases.