The correct answer is to **configure the Amazon Cognito identity pool to associate authenticated users with an IAM role that grants permissions to retrieve the protected objects**. This ensures that once users are authenticated, they are authorized through the proper IAM role that allows them to access specific S3 resources. This model uses the power of federated identity to provide fine-grained access control based on Cognito authentication.

The option to modify the S3 bucket access control list (ACL) is outdated and not ideal. ACLs provide basic object-level permissions, but they dont integrate cleanly with Cognito-authenticated users. Moreover, ACLs should be avoided in favor of IAM-based policies for better manageability and security best practices.

The suggestion to reupload the application files to the S3 bucket to eliminate eventual consistency issues is a misunderstanding of how Amazon S3 works. S3 provides strong read-after-write consistency for new objects and overwrites, so this would not resolve permission-related access problems.

The option to enable custom attribute mappings in the Cognito user pool is misleading in this scenario. While custom attributes are useful for enriching user profiles, they are not used to directly control access to AWS resources. IAM roles attached to the identity pool are the correct mechanism to manage access.

This question is important because it tests your understanding of integrating identity management with resource access control in AWS. A common pitfall is confusing the responsibilities of Cognito user pools (authentication) and identity pools (authorization). The trick to solving this question lies in recognizing that even after users are authenticated, their ability to access AWS services depends on being granted temporary credentials via the identity pools IAM roles.

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