When the administrator attempts to configure a Volume Group and connect an external iSCSI initiator,...

Nutanix Volumes documentation explains that external iSCSI clients use the iSCSI Data Services IP address for target discovery and connection. Nutanix specifically documents creating or updating the ISCSI Data Services IP Address on the cluster as part of enabling access to Volumes. If that step is missing, an external initiator can fail to discover or connect to the volume group correctly. Therefore B is the correct answer.

The other options are unrelated to the direct connectivity requirement. Microservices Infrastructure and Prism Central registration are not the necessary cluster-side prerequisites for an external iSCSI connection. LDAP directory configuration is also not the primary dependency being tested here. The key Nutanix platform requirement is that the cluster exposes the Volumes service via the configured Data Services IP. Without that, the initiator connection workflow breaks. So B is the authentic answer.