A developer is creating a mobile application that will not require users to log in.
What is the MOST efficient method to grant users access to AWS resources?

A. Use an identity provider to securely authenticate with the application.
B. Create an AWS Lambda function to create an IAM user when a user accesses the application.
C. Create credentials using AWS KMS and apply these credentials to users when using the application.
D. Use Amazon Cognito to associate unauthenticated users with an IAM role that has limited access to resources.