Which of the following are user authentication services managed by AWS?

Explanations:

Amazon Cognito is a user authentication service that provides user sign-up, sign-in, and access control. It is designed for developers to add user authentication to web and mobile apps easily.

AWS Lambda is a compute service that allows you to run code in response to events without provisioning or managing servers. It does not provide user authentication services.

AWS License Manager is a service that helps manage software licenses from various vendors, but it does not provide user authentication services.

AWS Identity and Access Management (IAM) is a service that helps you securely control access to AWS services and resources for your users. It provides mechanisms to authenticate users and manage permissions, making it essential for user authentication in AWS environments.

AWS CodeStar is a cloud-based service that helps you develop, build, and deploy applications quickly, but it does not manage user authentication services.