Which one of the following is the PKI operation that would likely cause out-of-band communication over the phone?
A. The client checks with the CA to determine whether a certificate has been revoked.
B. The client validates with the CA to determine if the peer that they are communicating with is the entity that is identified in a certificate.
C. A new signed certificate is received by the certificate applicant from the CA.
D. The CA administrator contacts the certificate applicant to verify enrollment data before the request can be approved.
