A developer is building authentication for a new mobile app. Users must be able to sign up, sign in, and access protected backend AWS resources. Which solution satisfies these requirements?

The correct solution is to use an Amazon Cognito identity pool. Cognito identity pools provide temporary AWS credentials to users, allowing them to access AWS services directly. By assigning default IAM roles for authenticated and guest users, you can control access to backend resources. Associating the identity pool with an identity provider (like Cognito User Pools, Facebook, Google, etc.) enables user sign-up and sign-in. The mobile app then integrates with this identity pool to obtain credentials. IAM Access Analyzer is for policy validation, not user authentication. Creating an IAM role and attaching it to an API Gateway endpoint only secures the API Gateway itself, not direct access for mobile app users to various backend AWS resources. A Cognito user pool handles user directories, sign-up, and sign-in, but it does not directly grant AWS resource access; an identity pool is needed for that.