Database Software

Hi,
This is a question from the 1z0-053 cert test. will be glad if anyone can assist :)

I have the following query result...:

select group_number, name, state from v$ASM_DISKGROUP;
and the output is:

0 DGROUP1 DISMOUNTED
2 DGROUP2 MOUNTED
3 DGROUP3 MOUNTED

my question is how can you understand from this, that "a disk associated with a disk group was discovered after the ASM instance initially opened"

thanks a lot!
Ori