An application requires that new users register using their social media accounts (OAuth/social identity providers). Which AWS service should the developer use to enable this sign-up method?

Amazon Cognito user pools provide a secure and scalable user directory that supports sign-up and sign-in for web and mobile applications. They can integrate directly with social identity providers like Facebook, Google, and Amazon, as well as enterprise identity providers through SAML or OpenID Connect. This allows users to register and authenticate using their existing social media accounts. IAM roles are used to grant permissions to AWS services and users, not for managing external user authentication. Amazon Cognito identity pools (federated identities) are used to grant AWS credentials to authenticated users, allowing them to access other AWS services, but they rely on a user pool or another identity provider for the initial authentication. AWS Directory Service provides managed Microsoft Active Directory, which is for enterprise directory services, not social media integration for application users.