The correct answer is Endpoint isolation.

Endpoint isolation immediately severs or restricts network connectivity for the affected workstation so it cannot make outbound connections or spread malicious activity. This containment action allows responders to preserve the device for forensic analysis while preventing further damage and lateral movement.

Threat and vulnerability risk management focuses on discovering and prioritizing vulnerabilities and exposures across systems to reduce risk over time. It is not an immediate containment action to stop an ongoing compromise.

Attack surface reduction policies are preventive controls that harden endpoints and block risky behaviors before incidents occur. They do not directly sever a device's current network connections to contain an active breach.

Automated investigation and remediation can investigate alerts and perform remediation steps based on playbooks and it may take automated actions. The explicit, fastest action to stop outbound activity on an actively compromised host is to isolate the device, which is the containment capability.

Custom indicators of compromise allow you to create detections and blocking rules for known IOCs and help hunting efforts. Creating and deploying indicators takes time and does not immediately stop all activity on a compromised host in the same direct way that isolation does.

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