What Azure solution should a development team use to automatically stop underutilized virtual machines outside business hours?

Azure Automation is the correct choice because it provides capabilities for process automation, including scheduling tasks like starting or stopping virtual machines. This allows the development team to define runbooks that automatically stop underutilized VMs outside business hours, optimizing costs. Azure Arc extends Azure management to on-premises and multi-cloud environments but doesn't directly automate VM shutdown schedules. Azure Monitor is used for collecting, analyzing, and acting on telemetry data, not for direct VM automation. Azure Key Vault securely stores and manages cryptographic keys and other secrets, which is unrelated to scheduling VM operations.