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

Explanations:

AWS Systems Manager Parameter Store is a fully managed service that provides secure storage for configuration data and secrets (such as passwords). It is a cost-effective option for storing configuration data and passwords, with support for versioning and access control. It is ideal for centralized management of these types of data.

AWS Secrets Manager is designed specifically for managing sensitive information like database credentials, API keys, and secrets. While it is suitable for storing passwords, it is more expensive compared to Parameter Store and is generally better for managing secrets with a shorter lifecycle or more complex rotation needs.

AWS Config is a service that provides configuration management and compliance tracking for AWS resources, not specifically for storing configuration data or passwords. It is used for auditing and compliance purposes, not for central storage of configuration data.

Amazon S3 is a general-purpose object storage service and is not specifically designed for securely storing configuration data or passwords. It lacks features like versioning, encryption, and access controls specifically tailored to secrets management. It is not the most cost-effective or secure option for this use case.