You create a Windows Workflow Foundation application by using Microsoft .NET Framework 3.5. The application is exposed as a Web service and uses confidential data. You need to ensure that only users in the Active Directory can access the workflow Web service method. What should you do?

A.
Configure the directory security setting of the IIS Web site so that only local users have access to the site.

B.
Add an instance of WorkflowRoleCollection class in the workflow as a field. Use the Add property to add users who can gain access to the site.

C.
Add an instance of the WebWorkflowRole class to the WorkflowRoleCollection collection that is represented by the WebServiceInputActivity.Roles property.

D.
Add an instance of the ActiveDirectoryRole class to the WorkflowRoleCollection collection that is represented by the WebServiceInputActivity.Roles property.