Final answer:
Azure Cosmos DB is Microsoft's globally distributed, multi-model database service that offers automatic indexing and scale-out capabilities.
Step-by-step explanation:
Azure Cosmos DB is Microsoft's globally distributed, multi-model database service. It is a NoSQL database that supports multiple data models, including document, key-value, graph, and column-family.
Azure Cosmos DB offers automatic indexing and scale-out capabilities, making it suitable for applications that require high availability, low latency, and global distribution.
Compared to options A (HDInsight) and C (Hadoop), Azure Cosmos DB is specifically designed for distributed and globally scalable database workloads.