Comprehensive and Detailed Explanation (ECIH-aligned):

Once malware is identified, ECIH guidance requires responders to analyze before eradication to understand scope, infection vectors, persistence mechanisms, and data impact. This ensures effective removal and prevents reinfection.

Option C is correct because forensic analysis allows investigators to determine how the malware entered the system, what data was accessed, and whether additional components are compromised. Without this understanding, containment and recovery efforts may be incomplete or ineffective.

Option A is a containment step but does not address root cause. Option B is a notification step that must be supported by verified facts. Option D protects future data but does not address the active malware.

Therefore, forensic analysis is the ideal primary action following detection, as emphasized in the ECIH malware handling process.