Answer: Azure Advisor

Azure Advisor is the optimal service for identifying underutilized or unused Azure virtual machines because it specifically analyzes resource utilization patterns (e.g., CPU, memory, network) and provides proactive recommendations to optimize costs by resizing or shutting down underutilized VMs. This aligns with Microsoft's documentation and the community consensus (83% selected A, with highly upvoted comments confirming Advisor's role). While Azure Cost Management + Billing (B) shows spending trends, it does not directly identify underutilization based on performance metrics. Azure reservations (C) are for pre-purchasing resources to save costs, not for identifying unused VMs. Azure Policy (D) enforces governance rules but does not analyze utilization.

Author: LeetQuiz Editorial Team