Your question is Explain the Singleton Design Pattern. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Explain the Singleton design pattern: how do you implement it and where is it useful?
Asked in the technical interview stage. Describe the pattern, show a practical implementation, and discuss thread safety, lazy initialization, testing, and situations where dependency injection or another design is preferable.