Which service would you use for a fully managed NoSQL database?

DynamoDB is the correct choice for a fully managed NoSQL database because it is specifically designed to handle large-scale, high-performance applications that require low-latency data retrieval. As a managed service, DynamoDB automatically takes care of backups, replication across multiple availability zones, scaling up or down based on demand, and provides built-in security features. This allows developers to focus more on application development rather than database management tasks.

Comparatively, AWS Aurora and Amazon RDS are relational database services, which typically follow SQL-based data models rather than NoSQL. Amazon S3, while a highly scalable storage service, does not function as a database itself but is used for storing objects and files rather than structured or semi-structured data typically found in NoSQL databases. Thus, for applications requiring a NoSQL approach, DynamoDB stands out as the best option.