Which attribute should you use?

You are implementing an ASP.NET application that will use session state in out-of-proc mode.
You add the following code.
public class Person
{
public string FirstName { get; set;}
public string LastName { get; set;}
}
You need to add an attribute to the Person class toensure that you can save an instance to session state.
Which attribute should you use?

A.
Bindable

B.
DataObject

C.
Serializable

D.
DataContract