What command is required to enable the Label Distribution Protocol on interface GigabitEthernet 0/3/0/0?

Refer to the configuration snippet below. A new IOS-XR router is being added to the network.
What command is required to enable the Label Distribution Protocol on interface GigabitEthernet
0/3/0/0?
Configuration:
mpls ldp
router-id 209.165.200.226

A.
interface GigabitEthernet0/3/0/0
mpls ldp

B.
mpls ldp
interface GigabitEthernet0/3/0/0