How can messages from a single mailbox archive be prevented from deletion?

Topic 7, Identify how to apply appropriate retention categories

Storage Expiry is enabled.

How can messages from a single mailbox archive be prevented from deletion?
A . clear the "Delete expired items from this archive automatically" check box in the archive properties
B . use the Tools > Disable Mailboxes option
C . mark the "Lock this category" check box in the Retention Category properties and restart the storage server
D . create and apply an EVPM initialization file with "NONDeletable=True" against the mailbox

Answer: A