Which of the following correctly configures simple per-VRF OSPF?

Which of the following correctly configures simple per-VRF OSPF?

A.
router ospf 11 vrf purple
redistribute bgp 1
network 172.16.0.0.0.0.255.255 area 0

B.
router ospf 11
address-family ipv4 purple
redistribute bgp 1 subnets
network 172.16.0.0.0.0.255.255 area 0

C.
router ospf 11 vrf purple
redistribute bgp 1 subnets
network 172.16.0.0.0.0.255.255 area 0

D.
router ospf 11
ip vrf purple
redistribute bgp 1 subnets
network 171.16.0.0.0.0.255.255 area 0