Which AWS service simplifies the migration of databases to AWS?

The AWS Database Migration Service (AWS DMS) is specifically designed to facilitate and simplify the migration of databases to AWS environments. It supports a variety of source databases, including both on-premises and cloud-based systems, and enables users to migrate their data with minimal downtime. AWS DMS automates much of the migration process, taking care of tasks such as data transformation, replication, and ongoing data changes, which significantly reduces the complexity and effort traditionally associated with database migrations.

In contrast, Amazon S3 is a scalable storage service primarily for storing and retrieving vast amounts of data, while AWS Config is a service for assessing, auditing, and evaluating the configurations of AWS resources, which does not pertain to database migrations. AWS Lambda is a serverless computing service that runs code in response to events and is not tailored for database migration tasks. Thus, the distinct function of AWS DMS in facilitating database migrations makes it the correct choice among the provided options.