A system administrator would like to rename volume group oldvg to newvg. This volume group resides on hdisk1. What is the appropriate procedure to perform this？（）

• A、reboot the server in maintenance mode；migratevg -y newvg oldvg；reboot the server in normal mode
• B、unmount all filesystems in the volume group；varyoffvg oldvg；migratepv -y oldvg -n newvg  varyonvg newvg
• C、unmount all filesystems in the volume group；varyoffvg oldvg；exportvg oldvg；importvg -y newvg hdisk1；mount all
• D、unmount all filesystems in the volume group；varyoffvg oldvg；for each logical volume in the volume group do cplv -v oldvg -y newvg；varyonvg newvg；mount all