While attempting to expand a file system， an administrator receives an error message indicating that the filesystem is not recognized. Running the ’lsfs’ command fails to display any output， but the ’df’ command is working and displays normal filesystems.  What is the likely cause of the problem？（）  

A.The /etc/filesystems file is missing.
B.The /dev/hd8 logical volume is corrupt.
C.The hosting volume group is not varied on.
D.The /var and /tmp filesystems may be full.