What is required on a Cisco IOS XR router to assign an interface to a VRF?

What is required on a Cisco IOS XR router to assign an interface to a VRF?

A.
Assign the VRF to the interface, and then re-enable Cisco Express Forwarding on the interface.

B.
Assign the VRF to the interface, and then reset the CE-to-PE routing protocol process.

C.
Shut the interface, assign the VRF to the interface, and then no shut the interface.

D.
Remove the IP address configuration on the interface, assign the VRF to the interface, and

then reconfigure the IP address on the interface.

Explanation:
http://www.cisco.com/en/US/docs/ios_xr_sw/iosxr_r3.5/mpls/configuration/guide/gc35v3.html#wp1
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