Comprehensive and Detailed Explanation (ECIH-aligned):

In the ECIH Incident Handling lifecycle, once a breach is detected, the IH&R team must focus on analysis and scoping to understand how the attack occurred, what systems were affected, and whether the attacker still has access.

Option D is correct because analyzing logs with Incident Response Automation and Orchestration (IRAO) tools allows rapid correlation of events, identification of attacker entry points, and determination of breach scope. ECIH stresses that zero-day incidents require deep forensic and timeline analysis to ensure complete containment and prevent recurrence.

Options A and C are important but depend on accurate breach understanding. Option B is premature without full incident context.

Therefore, log analysis and origin tracing is the correct primary focus.