You are developing an application that will use custom authentication and role-based security. You need to write a code segment to make the runtime assign an unauthenticated principal object to each running thread. Which code segment should you use?

A.
AppDomain domain = AppDomain.CurrentDomain;
domain.SetPrincipalPolicy(PrincipalPolicy.WindowsPrincipal);

B.
AppDomain domain = AppDomain.CurrentDomain;
domain.SetThreadPrincipal(new WindowsPrincipal(null));

C.
AppDomain domain = AppDomain.CurrentDomain;
domain.SetAppDomainPolicy( PolicyLevel.CreateAppDomainLevel());

D.
AppDomain domain = AppDomain.CurrentDomain;
domain.SetPrincipalPolicy( PrincipalPolicy.UnauthenticatedPrincipal);