what does that mean?

If a cipher lock has a door delay option, what does that mean?

A.
After a door is open for a specific period of time, the alarm goes off.

B.
It can only be opened during emergency situations.

C.
It has a hostage alarm capability.

D.
It has supervisory override capability.

Explanation:
There are several cases when a security guard would want to be alerted
when a door has been open for an extended period of time. It may be an indication
that something other than a person coming in and out of the door is taking place. A
security system can have a threshold set so that if the door is open past this time
period an alarm sounds.