Answer: Scalable index management and nearest neighbor search capability

**Correct Answer: C. Scalable index management and nearest neighbor search capability** **Explanation:** Option C is CORRECT because Amazon OpenSearch Service provides scalable index management and nearest neighbor search capability, which are essential features for building vector database applications. These features allow companies to efficiently store, manage, and search high-dimensional vector data, which is often used in machine learning and AI applications for tasks like similarity search. **Why other options are incorrect:** - **Option A**: While Amazon OpenSearch Service can integrate with Amazon S3 for backup and restore operations, this is not specifically related to vector database applications. - **Option B**: Geospatial indexing and queries are useful for location-based applications but are not the primary feature for building vector database applications. - **Option D**: Real-time analysis on streaming data is a general capability of OpenSearch, but vector database applications specifically require nearest neighbor search capabilities for similarity matching.

Author: Ritesh Yadav