A Windows Communication Foundation (WCF) application uses the following data contract.
You need to ensure that the following XML segment is generated when the data contract is
serialized. Which code segment should you use?

A.
<DataMember()> Public firstName As String <DataMember()> Public lastName As String

<DataMember(EmitDefaultValue:=True)> Public age As Integer = 0
<DataMember(EmitDefaultValue:=True)> Public ID As Integer = 999999999

B.
<DataMember(EmitDefaultValue:=False)> Public firstName As String = Nothing
<DataMember(EmitDefaultValue:=False)> Public lastName As String = Nothing
<DataMember(EmitDefaultValue:=True)> Public age As Integer = -1
<DataMember(EmitDefaultValue:=False)> Public ID As Integer = 999999999

C.
<DataMember(EmitDefaultValue:=True)> Public firstName As String
<DataMember(EmitDefaultValue:=True)> Public lastName As String <DataMember
(EmitDefaultValue:=False)> Public age As Integer = -1
<DataMember(EmitDefaultValue:=False)> Public ID As Integer = 999999999

D.
<DataMember()> Public firstName As String = Nothing <DataMember()> Public
lastName As String = Nothing <DataMember(EmitDefaultValue:=False)> Public age As
Integer = 0 < DataMember(EmitDefaultValue:=False)> Public ID As Integer = 999999999