Which Azure tool automates tasks such as stopping idle virtual machines to reduce costs?

Azure Automation is the correct choice because it provides cloud-based automation, operating system updates, and configuration capabilities. It includes features like Runbooks (PowerShell or Python scripts) that can be scheduled to perform routine tasks, such as stopping idle VMs to manage costs. Azure Logic Apps are used for orchestrating workflows and integrating services, but are less focused on scheduled task automation for infrastructure. Azure Functions are serverless compute services for executing small pieces of code in response to events, not primarily for scheduled infrastructure management. Azure DevOps is a suite of development tools for CI/CD, project management, and version control, unrelated to automated VM management.