Which of the following are Service Desk organizational structures?

Which of the following are Service Desk organizational structures?
1. Local Service Desk
2. Virtual Service Desk
3. IT Help Desk
4. Follow the Sun

A.
2, 3 and 4 only

B.
1, 2 and 4 only

C.
1, 2 and 3 only

D.
1, 3 and 4 only