Which of the following service desk organizational structures are described in service operation?

Which of the following service desk organizational structures are described in service
operation?
Local service desk
Virtual service desk
IT help desk
Follow the sun

A.
1, 2 and 4 only

B.
2, 3 and 4 only

C.
1, 3 and 4 only

D.
1, 2 and 3 only