Which tool can help you visualize CloudFormation stacks and their resources?

AWS CloudFormation Designer is the correct tool for visualizing CloudFormation stacks and their resources. This graphical tool allows users to create, modify, and visualize CloudFormation templates in a user-friendly interface. With CloudFormation Designer, you can view the various resources defined in your template, their relationships, and how they will be instantiated within the AWS environment. This capability simplifies the process of understanding and managing the architecture of your applications on AWS.

The other tools mentioned serve different purposes that do not focus specifically on visualizing CloudFormation stacks. For instance, AWS Systems Manager is primarily used for operational tasks such as automation, maintaining security and compliance, and managing resources across AWS environments. AWS CodePipeline is a continuous integration and continuous delivery service that automates the building, testing, and deployment of applications, whereas AWS Route 53 is a scalable DNS and domain name registration service that manages domain names and routes internet traffic to the appropriate resources, rather than visualizing infrastructure.