Which of the following statements is true about using crontab and at to execute tasks?

A.
Commands scheduled with crontab are executed by at.

B.
Both commands can be used to schedule a weekly task to run for a user.

C.
User access control for both commands can be managed with .deny files in \var/adm/cron.

D.
Both commands preserve the current environment, including the user ID and current working
directory

Explanation: