which configuration command must the administrator enter to accomplish this?

Examine the diagram. A network administrator has recently installed the above switched network using 3550s and would like to control the selection of the root bridge. Which switch should the administrator configure as the root bridge and which configuration command must the administrator enter to accomplish this?

A.
DSW11(config)# spanning-tree vlan 1 priority 4096

B.
DSW12(config)# set spanning-tree priority 4096

C.
ASW13(config)# spanning-tree vlan 1 priority 4096

D.
DSW11(config)# set spanning-tree priority 4096

E.
DSW12(config)# spanning-tree vlan 1 priority 4096

F.
ASW13(config)# set spanning-tree priority 4096