The network administrator is adding a new N1Kv to the vCenter， however， the administrator does not see the new switch under the networking tab of vCenter.    The administrator issues the following command on the VSM to troubleshoot：        VSM# show svs connections  connection VC://  ip address： 10.10.10.30  remote port： 80  protocol： vmware-vim https  certificatE. default  datacenter namE. DC1  DVS uuiD. 67 32 30 50 a6 d2 49 64-9e 1c 5f 49 e3 af 55 99  config status： Disabled  operational status： Disconnected sync status： -  version： -        When attempting to fix the issue， the following error is seen：        VSM-PRI-188# conf    VSM-PRI-188（config）# svs connection VC  VSM-PRI-188（config-svs-conn）# connect  ERROR： [VMWARE-VIM] Extension key was not registered before its use        What is the cause of the error？（）

• A、 Missing control VLAN in VSM configuration
• B、 Missing packet VLAN in VSM configuration
• C、 VSM has no network connection to vCenter
• D、 VSM extension key is not installed on vCenter
• E、 vCenter extension key is not installed on VSM