Which two files are responsible for allowing users to execute cron jobs?

A.
/etc/cron.allow

B.
/var/spool/cron.allow

C.
/var/spool/cron.allow

D.
/etc/cron.deny

Explanation/Reference:
From http://docs.sun.com/app/docs/doc/805-7229/6j6q8svfu?a=view:

You can control access to crontab by using two files in the /etc/cron.d directory: cron.deny and cron.allow. These

files permit only specified users to perform crontab tasks such as creating, editing, displaying, or removing their

own crontab files. The cron.deny and cron.allow files consist of a list of user names, one per line. These access

control files work together like this:
    *      If cron.allow exists, only the users listed in this file can create, edit, display, or remove crontab

files.
    *      If cron.allow doesn’t exist, all users may submit crontab files, except for users listed in cron.deny.
    *      If neither cron.allow nor cron.deny exists, superuser privileges are required to run crontab.
Superuser privileges are required to edit or create the cron.deny and cron.allow files.