The clean way to read this scenario is to separate what is merely present in the environment from the single Nutanix construct that actually satisfies the requirement. The correct response is A, meaning “Update the ERPs for Tenant-B-VPC.”. Externally Routable Prefixes determine which overlay prefixes are advertised beyond the VPC. If the ERP does not cover the workload subnet, upstream devices never learn a valid return path, even when the local VPC appears healthy. Operationally, Flow Virtual Networking should be checked from the control plane outward: gateway health, peering state, route advertisement, ERP coverage, external path, and MTU when encapsulation is involved.

In other words, this is less about broad infrastructure suspicion and more about finding the exact Nutanix decision point that explains the behavior. Notice that B does not fit because it targets a different layer of the Nutanix networking and security stack than the one causing the outcome here. C does not fit because it targets a different layer of the Nutanix networking and security stack than the one causing the outcome here. That is the underlying Nutanix principle being validated: solve the issue at the feature that owns the behavior, not by changing unrelated infrastructure settings that happen to sound network-oriented.