Which of the following entries are NOT valid in /etc/raidtab?

Which of the following entries are NOT valid in /etc/raidtab?

A.
superblock-persistent

B.
chunk-size

C.
nr-spare-disks

D.
nr-raid-disks

Explanation:
From the man pages:
These are the possible entries in /etc/raidtab:
raiddev nr-raid-disks nr-spare-disks persistent-superblock parity-algorithm chunk-size size device
raid-disk spare-disk parity-disk failed-disk