Create a WCF service

You are tasked with adding a method named GetCurrentStockPrice to an existing service. The Service is named QuoteService and it implements the IQuoteService Contract. How should you go about adding this new method? (Choose all that apply)

Add the OperationContract attribute to the method definition.
Create a new ServiceContract class and add the GetCurrentStockPrice method to it.
Add the OperationBehavior attribute to the method definition.
Add the method definition to the IQuoteService Contract.