There is a WCF (Windows Communication Foundation) service PassGuideService.
PassGuideService has a callback contract.
There is a client application PassGuideClient.
PassGuideClient calls PassGuideService.

How can you ensure that PassGuideClient and PassGuideService can communicate? Select two.

A.
Use the OperationContractAttribute..

B.
On PassGuideService..

C.
On PassGuideClient..

D.
..set set the Async Pattern property value to false

E.
..set set the Async Pattern property value to normal

F.
..use GetCallbackChannel (Of T)

G.
..add a proxy derived from DuplexClientBase (Of TChannel)

Explanation: