Which steps are mandatory to enable Direct NFS？（）   1. Mount all required file systems using the kernel NFS driver.  2. Create an oranfstab file containing the attributes for each NFS server to be accessed using Direct NFS.    3. Replace the ODM library libodm11.so_stub with libodm11.so.

• A、 2 and 3
• B、 1 and 3
• C、 1 and 2
• D、 1，2 and 3