The newest OSPFv3 configuration approach utilizes a single OSPFv3 process. It is capable of supporting IPv4 and IPv6 within a single OSPFv3 process. OSPFv3 builds a single database with LSAs that carry IPv4 and IPv6 information. The OSPF adjacencies are established separately for each address family. Settings that are specific to an address family (IPv4/IPv6) are configured inside that address family router configuration mode.
Running single OSPFv3 for both IPv4 and IPv6 is supported since Cisco IOS Software Release
15.1(3)S.
The new-style OSPFv3 process is enabled using the router ospfv3 process-number command.
Within the OSPF process configuration mode, the OSPF process ID is defined (using the router- id ospf-process-ID command).
OSPFv3 New-Style OSPF Configuration Commands:

Therefore answer B is the best answer here but in this answer, the configuration mode is not correct. It should be interface mode (config-if)#, not router mode (config-router)#.
Reference: https://www.ciscopress.com/articles/article.asp?p=2294214&seqNum=4