Which statement is true about the installation of Virtual Infrastructure Web Access?

Which statement is true about the installation of Virtual Infrastructure Web Access?

A.
It is always installed on VirtualCenter and is optional on ESX Server.

B.
It is optional on both ESX Server and VirtualCenter.

C.
It is always installed on ESX Server and VirtualCenter.

D.
It is always installed on ESX Server and is optional on VirtualCenter.