Amazon GuardDuty is the fully managed AWS threat detection service designed to analyze CloudTrail events, VPC Flow Logs, and DNS logs to identify suspicious and malicious activity. It uses threat intelligence and behavioral models to detect patterns such as unusual API calls, anomalous network connections (including known malicious destinations), and suspicious DNS activity---directly matching the scenario requirements. Macie is focused on discovering and protecting sensitive data (especially in S3) through classification and data exposure detection, not broad threat detection across API/network/DNS. AWS Config is a configuration compliance and drift monitoring service; it tracks resource configurations and policy compliance but does not provide threat detection based on network and activity logs. Security Hub aggregates and normalizes findings from multiple AWS security services and partners; it is a central view and compliance/finding management layer, but it relies on services like GuardDuty to generate threat findings. From a SOC perspective, GuardDuty provides the near-real-time detection signals the team needs, and those findings can be forwarded to SIEM/SOAR workflows for triage and response.