A public-facing website recently had problems where some links returned missing pages and others returned incorrect content, even though the infrastructure and resources appeared healthy and logs showed no errors. Administrators only found out after user reports. The company wants an early detection system for these kinds of functional issues with minimal operational effort and fast deployment. Which option meets these needs?

The correct answer is to create an Amazon CloudWatch Synthetics canary. Synthetics canaries are designed for proactive monitoring of website functionality from an end-user perspective. They can simulate user clicks and form submissions, checking for broken links, incorrect content, and other functional issues that might not generate system-level errors. The Synthetics Recorder plugin simplifies script creation, and alarms can be configured for immediate notification. This approach provides early detection with minimal operational overhead. Modifying the application to emit custom error events is reactive and requires code changes, which is not fast deployment. Deploying a Lambda to exercise endpoints is a viable option but requires more custom development and maintenance compared to a managed canary. Enabling Application Insights is for monitoring application health and performance metrics, not for proactively testing website functionality like broken links or incorrect content from a user's perspective.