Which AWS service will provide a secure and cost-effective solution for retaining these files?

Explanations:

Amazon DynamoDB is a NoSQL database service that is optimized for high-speed transactions and not designed for storing large files like audio recordings.

Amazon S3 Glacier is a low-cost cloud storage service designed for data archiving and long-term backup. It is suitable for retaining call recordings for 6 years, and S3 Glacier provides retrieval times in hours, which meets the 48-hour requirement.

Amazon Connect is a cloud-based contact center service but does not provide storage for recordings. It is primarily focused on enabling customer service interactions rather than file retention.

Amazon ElastiCache is a managed caching service that improves application performance but is not designed for long-term storage of files, making it unsuitable for retaining call recordings.