Which AWS service provides a way to visualize application performance?

Amazon CloudWatch is the correct choice because it is specifically designed to monitor and visualize application performance. It provides comprehensive metrics and logs that help users track the health and performance of their applications run on AWS. CloudWatch enables users to create dashboards that visualize performance metrics in real-time, allowing for quick analysis and troubleshooting. It also offers features such as alarms and automatic scaling based on set thresholds, further enhancing its capabilities in visualizing and managing application performance effectively.

The other services listed serve different purposes: AWS CloudTrail focuses on governance, compliance, and operational risk management by logging API calls made on your account, providing a history of AWS API calls for effective monitoring and auditing. AWS Config is tailored for resource compliance and auditing configurations of AWS resources, helping to maintain compliance and governance but does not focus on performance visualization. AWS CodePipeline is a continuous integration and continuous delivery service designed to help you automate your release process, which is essential for deployment but does not provide insights into application performance itself.