A cluster administrator is concerned about using the forced varyon resource group function. Although the function provides increased data availability if it is enabled for a cluster resource group， management is concerned about data integrity.  If a varyonvg command fails， an HACMP forced varyon will only occur if which of the following is true？（）  

• A、 A loss of quorum has occurred on one of the disks in the failed volume group.
• B、 Selective fallover caused by an application moves a resource group to a takeover node.
• C、 A check is made to ensure at least one complete copy of all data is available in the volume group.
• D、 The MISSING_PV=TRUE environment variable has been set causing the volume group to be forced online.