A SIEM (Security Information and Event Management) system aggregates logs from diverse sources, analyzes them, and generates alerts on suspicious activities. It provides centralized monitoring and incident detection. SCADA (B) is industrial control, SNMP (C) is a protocol for network management, and SCAP (D) is a standard for security content automation. SIEMs are foundational in Security Operations monitoring#6:Chapter 14 CompTIA Security+ Study Guide#.