Which file specifies the user accounts can NOT submit jobs via at or batch?

(Provide the full path and filename)

Answer: /etc/at.deny

Explanation/Reference:
The  /etc/at.allow  and  /etc/at.deny  files  determine which user can submit commands for later execution via at(1) or batch(1). The format of the files is a list of usernames, one on each line. The superuser may always use at. If the file /etc/at.allow exists, only usernames mentioned in it are allowed to use at. If /etc/at.allow does not exist, /etc/at.deny is checked.