A developer is automating daily shutdown and startup of non-production VMs to lower costs. Which tool should they use?

Azure Automation is the correct choice because it allows you to automate repetitive tasks and manage Azure resources, including scheduling the shutdown and startup of virtual machines. This directly addresses the need for cost optimization by ensuring non-production VMs are only running when necessary. Azure Monitor is used for collecting, analyzing, and acting on telemetry data from your Azure and on-premises environments, not for scheduling actions. Azure App Service is a platform for building, deploying, and scaling web apps and APIs, and doesn't provide VM automation capabilities. Azure Policy helps enforce organizational standards and assess compliance, but it doesn't automate operational tasks like VM start/stop schedules.