Which AWS service or capability will meet these requirements MOST cost-effectively?

Explanations:

AWS Systems Manager Parameter Store is designed to store configuration data and sensitive information like passwords securely. It provides a cost-effective way to manage parameters, supports versioning, and integrates well with other AWS services. The first 10,000 parameters are free, making it suitable for centralized storage without incurring significant costs.

AWS Secrets Manager is focused on managing secrets, such as API keys and database credentials, and provides automatic rotation of secrets. While it is more secure for managing sensitive data, it is generally more expensive than Parameter Store, especially for large volumes of secrets, making it less cost-effective for the scenario described.

AWS Config is a service for tracking AWS resource configurations and compliance over time. It does not provide capabilities for storing configuration data or passwords, making it unsuitable for the company’s requirements.

Amazon S3 is an object storage service suitable for storing and retrieving any amount of data but lacks specific features for managing configuration data and sensitive information securely. It would require additional management and security measures, making it less ideal for the requirements presented.