An organization wants to host a high-traffic web application that automatically scales based on demand. Which service best fits?

Azure App Service is the best fit because it is a fully managed platform for building, deploying, and scaling web apps. It natively supports automatic scaling based on demand, which is crucial for high-traffic applications. Azure Virtual Machines require manual configuration and management of scaling, adding operational overhead. Azure Batch is designed for large-scale parallel and high-performance computing, not general web hosting. Azure Arc extends Azure management to on-premises, multi-cloud, and edge environments, and is not a hosting service itself.