To prevent a specific user from scheduling tasks with at, what should the administrator do?

A.
Add the specific user to /etc/at.allow file.

B.
Add the specific user to nojobs group.

C.
Run the following: atd deny [user].

D.
Add the specific user to /etc/at.deny file.

E.
Add the specific user to [deny] section in the /etc/atd.conf file.