Which two actions should you perform?

A Windows Communication Foundation (WCF) solution uses the following contract:

[ServiceContract(SessionMode=SessionMode.Allowed)]
public interface IMyService
{
[OperationContract(IsTerminating=false)]
void Initialize();
[OperationContract(IsInitiating=false)]
void DoSomething();
[OperationContract(IsTerminating=true)]
void Terminate();
}

You need to change this interface so that:
* lnitialize is allowed to be called at any time before Terminate is called.
* DoSomething is allowed to be called only after Initialize is called, and not allowed to be called after Terminate is called.
* Terminate will be allowed to be called only after Initalize is called.

Which two actions should you perform? (Each correct answer presents part of the sdution. Choose two)

A.
Change the ServiceContract attribute of the IMyService interface to the following.
[ServiceContract(SessionMode=SessionMode.Required)]

B.
Change the ServiceContract attrbute of the IMyService interface to the following
[ServiceContract(SessionMode=SessionMode.Allowed)]

C.
Change the OperationContract attribute of the Initialize operation to the following.
[OperationContract(IsInitiating = true, IsTerminating = false)]

D.
Change the OperationContract attribute of the Terminate operation to the following
[OperationContract(IsInitiating = false, IsTerminating = true)]

Explanation:
OperationContractAttribute.IsInitiating
Gets or sets a value that indicates whether the method implements an operation that can initiate a session on the server (if such a session exists).

OperationContractAttribute.IsInitiating Property
(http://msdn.microsoft.com/en-us/library/system.servicemodel.operationcontractattribute.isinitiating.aspx)

Example:

The following example is a service that implements a service contract that specifies three methods.
The service requires a session. If a caller’s first call is to any operation other than MethodOne,
the channel is refused and an exception is thrown. When a caller initiates a session by calling MethodOne,
that caller can terminate the communication session at any time by calling MethodThree.
MethodTwo can be called any number of times during a session.

C#
[ServiceContract(SessionMode=SessionMode.Required)]
public class InitializeAndTerminateService
{
[OperationContract(IsOneWay=true, IsInitiating=true, IsTerminating=false)]
public void MethodOne()
{
return;
}

[OperationContract(IsInitiating=false, IsTerminating=false)]
public int MethodTwo(int x, out int y)
{
y = 34;
return 0;
}

[OperationContract(IsOneWay=true, IsInitiating=false, IsTerminating=true)]
public void MethodThree()
{
return;
}
}