The correct answer is A — User and entity behavior analytics (UEBA).

WGU Cybersecurity Architecture and Engineering (KFO1 / D488) explains that UEBA tools analyze patterns of user and entity behavior to detect anomalies that could indicate insider threats, compromised accounts, or advanced persistent threats (APTs). UEBA focuses on deviations from normal activity patterns to identify risks that traditional signature-based systems might miss.

HSMs (B) protect cryptographic keys but do not monitor behavior. Antivirus tools (C) detect known malware but do not perform behavioral analytics. Two-factor authentication (D) secures access but does not detect unusual behavior patterns.

Reference Extract from Study Guide:

"User and entity behavior analytics (UEBA) identifies potential security threats by analyzing deviations from typical user and system activity patterns."

— WGU Cybersecurity Architecture and Engineering (KFO1 / D488), Threat Detection Technologies