A system administrator has a two-disk volume group （testvg） with one logical volume （testlv） which has just been mirrored across both disk drives. Which of the following commands can be used to turn off quorum？（）

A.chvg -Qn testvg
B.chlv -Qn testlv
C.varyoffvg testvg； varyonvg -Qn testvg
D.varyoffvg testvg； exportvg testvg； importvg -Qn testvg； varyonvg testvg