Answer: Amazon ElastiCache

## Explanation **Amazon ElastiCache** is the correct choice because: - **In-memory data store**: ElastiCache provides fully managed in-memory data stores using Redis or Memcached - **Open source compatibility**: It supports popular open-source in-memory caching engines (Redis and Memcached) - **Managed service**: AWS handles the operational overhead while maintaining compatibility with open-source APIs **Why other options are incorrect**: - **Amazon DynamoDB**: NoSQL database service, not primarily an in-memory data store - **Amazon Elastic Block Store (EBS)**: Block-level storage volumes for EC2 instances, not an in-memory data store - **Amazon Redshift**: Data warehousing service for analytics, not an in-memory caching solution ElastiCache is specifically designed for use cases requiring high-performance, low-latency in-memory caching with open-source compatibility.

Author: Ritesh Yadav