You need to monitor Azure resource costs and identify underutilized resources. Which tool provides this capability?

Correct answer: Azure Cost Management + Billing

Option A is correct because Azure Cost Management + Billing provides dashboards, budgets, cost alerts, and detailed usage reports that allow administrators to monitor spending trends and identify idle or underutilized resources through features like Azure Advisor recommendations integrated into the cost view. Option B is wrong because Azure Monitor focuses on performance metrics, logs, and diagnostics for applications and infrastructure health, not on financial cost analysis or resource rightsizing. Option C is wrong because Application Insights is an APM (Application Performance Monitoring) service specifically for tracking application telemetry such as request rates, exceptions, and dependencies, not cloud spending. Option D is wrong because while Azure Advisor does surface some cost recommendations, it is a best-practice recommendation engine covering reliability, security, and performance as well, whereas Cost Management + Billing is the dedicated tool for comprehensive cost monitoring and billing analysis.