After containment and remediation, one of the final steps in incident response is user education. Since the root cause was a phishing attack, it is essential to educate users about identifying phishing attempts, safe browsing practices, and how to handle suspicious communications. This improves overall security posture and helps prevent future incidents.

A. Installing additional tools may be helpful but is a long-term step.

C. Flashing router firmware is not warranted unless the network hardware is known to be compromised.

D. Suggesting more advanced tools might be excessive given that the EDR successfully contained the incident.