WCF特点描述正确的是（）

A.[ServiceContract]public Class Service1{[Operation Contract]double Add（double n1，double n2）}
B.[ServiceContract]public Interface IService1{[Operation Contract]double Add（double n1，double n2）}
C.[ServiceContract]public Interface IService1{double Add（double n1，double n2）}
D.public Interface IService1{[Operation Contract]double Add（double n1，double n2）}

A.CancellationTokenSource
B.CancellationToken
C.TaskCreationOption
D.TaskStatus

A.Lambda
B.Action
C.Func
D.Tuple