When converging an existing vSphere environment into VCF, certain architectural requirements must be satisfied.
The VCF 9.0 Convergence Guide states that:
The vCenter Server must be running on a cluster it manages (self-managed cluster) to allow SDDC Manager to take ownership during convergence.
Incorrect options:
Baselines (A) are not required; in fact, VCF requires image-based lifecycle management after convergence.
VDS version 7.0 (C) is not a documented prerequisite.
NSX (D) is not required prior to convergence; NSX can be deployed during workload domain bring-up.
Therefore, the required prerequisite is:
vCenter Server VM must be hosted on a cluster it manages.