Final answer:
Health Checks is a feature of Route53 that can improve service availability by monitoring the health and performance of resources and automatically routing traffic to healthy resources.
Step-by-step explanation:
The feature of Route53 that can help improve the availability of service to customers is Health Checks. Health Checks allow you to monitor the health and performance of your resources, such as web servers or load balancers, and automatically route traffic to healthy resources. With Health Checks, you can set up various types of checks to ensure that your services are operating correctly and efficiently. For example, you can monitor the status of an HTTP endpoint by sending periodic HTTP requests to the endpoint and verifying the response code.