Which of the following is correct?

The following is an excerpt from a procmail configuration file:

:0 c
* ! ^To: backup
! backup

Which of the following is correct?

A.
All mails will be backed up to the path defined by $MAILDIR .

B.
All mails to the local email address backup will be stored in the directory backup.

C.
A copy of all mails will be stored in file backup.

D.
A copy of all mails will be send to the local email address backup.

E.
Mails not addressed to backup are passed through a filter program named backup.