What is the cause of the error?

When starting up your ASM instance, you receive the following error:
SQL> startup pfile=?/dbs/init+ASM.ora ASM instance started
Total System Global Area 104611840 bytes
Fixed Size 1298220 bytes
Variable Size 78147796 bytes
ASM Cache 25165824 bytes
ORA-15032: not all alterations performed
ORA-15063: ASM discovered an insufficient number of disks for disk group "DGROUP3"
ORA-15063: ASM discovered an insufficient number of disks for disk group "DGROUP2"
ORA-15063: ASM discovered an insufficient number of disks for disk group "DGROUP1"
In trying to determine the cause of the problem, you issue this query:
SQL> show parameter asm
NAME TYPE VALUE
———————————— ———– ————————-_
asm_allow_only_raw_disks boolean FALSE
asm_diskgroups string DGROUP1, DGROUP2, DGROUP3
asm_diskstring string
asm_power_limit integer 1
asm_preferred_read_failure_groups string
What is the cause of the error?

A.
The ASM_DISKGROUPS parameter is configured for three disk groups: DGROUP1, DGROUP2, and DGROUP3. The underlying disks for these disk groups have apparently been lost.

B.
The format of the ASM_DISKGROUPS parameter is incorrect. It should reference the disk group numbers, not the names of the disk groups

C.
The ASM_POWER_LIMIT parameter is incorrectly set to 1. It should be set to the number of disk groups being attached to the ASM instance.

D.
The ASM_DISKSTRING parameter is not set; therefore disk discovery is not possible.

E.
There is insufficient information to solve this problem.