A system administrator has been asked to migrate the dev_vg volume group from server A to server B. The dev_vg volume group contains a single filesystem named "/development". To prepare for migration, which of the following is the correct sequence of commands for removing the volume group from server A?()
A、exportvg dev_vg; umount /development; varyoffvg dev_vg
B、varyoffvg dev_vg; umount /development; exportvg dev_vg
C、umount /development; exportvg dev_vg; varyoffvg dev_vg
D、umount /development; varyoffvg dev_vg; exportvg dev_vg