Which permission class should you use?

You work as a developer at Company.com. You are creating an assembly named Company1. Company1 contains a public method. The global cache contains a second assembly named Company2.
You must ensure that the public method is only called from Company2.
Which permission class should you use?

A.
GacIdentityPermission

B.
PublisherIdentityPermission

C.
DataProtectionPermission

D.
StrongNameIdentityPermission