Which service provides centralized visibility into potential threats across Azure and on-premises environments?

Microsoft Defender for Cloud (formerly Azure Security Center) is the correct answer because it offers unified security management and advanced threat protection across hybrid cloud workloads, including Azure and on-premises resources. It provides security posture management, threat protection, and centralized visibility into security alerts and recommendations. Azure Arc extends Azure management to on-premises and multi-cloud environments but doesn't primarily focus on threat visibility. Azure Monitor collects and analyzes telemetry data but isn't a security-specific threat detection service. Azure Advisor provides recommendations for cost, performance, reliability, operational excellence, and security, but its security recommendations are a subset of Defender for Cloud's comprehensive threat visibility.