It was announced that only when visitors’ identities_______ been checked, _______to get in.

A．has; they are allowed                        B．had; were they allowed

C．had; they were allowed                    D．has; are they allowed

It was announced that only when visitors' identities ________ been checked, ________to get in．

1. A.
   has; they are allowed
2. B.
   had; were they allowed
3. C.
   had; they were allowed
4. D.
   has; are they allowed