How can a specific user be prevented from scheduling tasks with at?

How can a specific user be prevented from scheduling tasks with at?
A . By adding the specific user to the /etc/at.allowfile.
B . By adding the specific user to the [deny] section in the /etc/atd.conffile.
C . By adding the specific user to the nojobs group.
D . By adding the specific user to the /etc/at.denyfile.
E . By executing the atd –deny[user] command.

View Answer

Answer: D