Which Azure service lets a developer run containerized web apps without managing the underlying infrastructure?

Azure Container Instances (ACI) is the correct answer because it allows you to run Docker containers directly in Azure without needing to provision or manage virtual machines or orchestrators. It's ideal for simple, single-container workloads where you don't need the full orchestration capabilities of Kubernetes. Azure Kubernetes Service (AKS) is a managed Kubernetes offering, which is for orchestrating many containers and managing complex microservices, requiring more configuration than ACI. Azure Functions is a serverless compute service for event-driven code execution, not primarily for running general-purpose containerized web apps. Azure Virtual Machines (VMs) provide IaaS (Infrastructure as a Service), meaning you are responsible for managing the operating system and all software layers, including container runtimes, which contradicts the requirement of not managing underlying infrastructure.