The eradication phase in incident response involves eliminating the root cause of the incident and strengthening defenses to prevent reoccurrence. In this case:
Intrusion Prevention System (D): Adding new rules to the IPS to detect and block malicious activity on TCP
/135 is a direct eradication step to remove the threat's entry point and prevent future attacks.
Centralized User Management (C): Hardening user accounts, removing unnecessary permissions, and applying tighter authentication/authorization measures helps eliminate the possibility that threat actors could exploit weak or mismanaged accounts to continue accessing the system.
Although anti-malware software (A) and enterprise block listing (E) are valuable, the most direct eradication steps here specifically involve managing network access (via IPS) and strengthening user controls (via centralized user management), especially when TCP/135 (MSRPC endpoint mapper) can be used to enumerate services and potentially access vulnerable endpoints remotely.
This aligns with best practices outlined in incident response frameworks (such as the NIST SP 800-61 and referenced resources), which emphasize closing the exploited entry points (in this case, TCP/135) and removing any lingering access points through user management and network control enhancements.
Reference:
CyberOps Technologies (CBRFIR) 300-215 study guide, Chapter: Understanding the Incident Response Process, Eradication Phase, page 105-106.
External Reference: "The Core Phases of Incident Response - Remediation," Cipher blog [1].
External Reference: "Service Overview and Network Port Requirements," Microsoft documentation [2].

The alert shown is based on a Snort rule for a Unicode directory traversal attack against IIS web servers (Microsoft platform). The key detail here is the payload content " ../..%c0%af../ " which is a classic IIS- specific exploit related to CVE-2000-0884.
Since the company only uses Unix systems, they are not vulnerable to this IIS-specific attack. Therefore, these alerts are triggered by irrelevant traffic or misapplied signatures, resulting in False Positives.
As defined in the Cisco CyberOps guide:
"False Positive: an alert is generated for traffic that is not actually malicious or relevant to the protected environment".

Process Explorer is an advanced Windows-based utility that shows real-time data about running processes, CPU usage, services, DLLs, and handles. It is specifically designed for this kind of investigation and is part of the Sysinternals Suite.

Data loss prevention is the control most directly aligned with the incident's root cause: an authorized insider removed sensitive customer information. DLP policies can identify regulated or confidential content, inspect transfers, alert on abnormal movement, and block unauthorized exfiltration through supported channels. Cisco explains that DLP uses rules to find sensitive information and detect abnormal transfers, including intentional disclosure of customer data. This makes option D a targeted post-incident recommendation under CBRFIR objectives 3.4 and 3.5. A penetration test may reveal exploitable technical weaknesses, antivirus addresses malware, and universal password changes address credential compromise; none directly controls misuse of legitimate access to move protected data. DLP should still be combined with least privilege, access reviews, logging, and user-behavior monitoring, but among the listed choices it best reduces recurrence. See Cisco's DLP overview .