Design a scalable MongoDB schema for user authentication incorporating role-based access control, tailored for advanced users familiar with MongoDB and database design principles.** Outline your approach by detailing:** ## 1. **Schema Design**: Define the structure for user authentication and role-based access control, considering scalability and performance. ## 2. **Indexing Strategies**: Explain how you would implement indexing to optimize query performance for large-scale applications. ## 3. **Query Optimization Techniques**: Describe methods to enhance query efficiency, focusing on scalability and performance considerations. Include concrete examples to illustrate each point, emphasizing how your design addresses the challenges of large-scale applications. Ensure your explanation is technically detailed and assumes a high level of MongoDB and database design knowledge.