Following a successful migration，it is highly recommended that concurrent Volume Groups be Converted to enhanced concurrent capable Volume Groups. In order to follow this recommendation，what step must be completed first？（）
- A The Volume Groups must be changed with chvg -E vgname.
- B The Volume Groups must be a member of a resource group and must be varied on al nodes of the cluster.
- C The Volume Groups must be a member of a resource group and must be varied off all nodes of the cluster.
- D The Volume Grups cannot be changed to enhanced concurrent capable because they must be recreated with mkvg -C vgname.