The computer incident response team at a multinational company has determined that a breach of sensitive data has occurred in which a threat actor has compromised the organization’s email system. Per the incident response procedures, this breach requires notifying the board immediately. Which of the following would be the BEST method of communication?
A. Post of the company blog
B. Corporate-hosted encrypted email
C. VoIP phone call
D. Summary sent by certified mail
E. Externally hosted instant message