which configuration mode?

With Layer 3 MPLS VPN implementations on Cisco IOS XR PE routers, an interface is assigned to
a VRF using the vrf command in which configuration mode?

A.
RP/0/RP0/CPU0:PE(config-vrf)#

B.
RP/0/RP0/CPU0:PE(config-if)#

C.
RP/0/RP0/CPU0:PE(config-bgp)#

D.
RP/0/RP0/CPU0:PE(config-bgp-af)#

Explanation: