A startup wants to deploy a highly scalable web application without managing the underlying servers. Which Azure compute option should they choose?

Azure App Service is the best choice for a highly scalable web application without managing underlying servers. It's a fully managed Platform as a Service (PaaS) offering, meaning Azure handles the operating system patching, security updates, and infrastructure scaling. This allows the startup to focus solely on their application code. Azure App Service provides built-in auto-scaling capabilities and supports various programming languages. Azure Functions is a serverless compute service best suited for event-driven, short-running tasks, not a full web application. Azure Virtual Machines (IaaS) require the user to manage the operating system and all software, which contradicts the requirement of not managing servers. Azure Kubernetes Service (AKS) is for orchestrating containerized applications and, while powerful, involves more operational overhead than App Service, making it less ideal for a startup prioritizing minimal server management.