On an ESX Server, a particular user is assigned the Administrator role. However, when
that user logs into the vCenter Server, they have Read Only rights.
What most likely caused this?

A.
ESX Server roles do not propagate to the vCenter Server.

B.
The ESX Server is not authenticating using NIS.

C.
The user is logging in with a different password.

D.
The vCenter Server is not a member of an Active Directory domain.

Explanation:
vSphere Basic System Administration vCenter Server 4.0 ESX 4.0 ESXi 4.0, page 211.
The privileges and roles assigned on an ESX/ESXi host are separate from the privileges
and roles assigned on a vCenter Server system. When you manage a host using vCenter
Server, only the privileges and roles assigned through the vCenter Server system are
available. If you connect directly to the host using the vSphere Client, only the privileges
and roles assigned directly on the host are available, (A).