An executive in a computer software firm works with his office door closed. at the same time every hour heopens the door to see what his employees are doing. the employees have learned to work especially hard duringthe five minutes before and while the door is open. their work pattern is typical of responses that are reinforcedon a schedule.
a. fixed-interval
b. fixed-ratio
c. variable-ratio
d. variable-interval

A.fixed-interval

Explanation:

As we know that a interval is called fixed interval if things happen after a fixed time.For example a train come every morning at 7 AM this is a fixed time interval.

Here door  open after every hours and he checks that what his employees is doing.So just 5 minute before he opens the door every employees become alert and start to work as like he is doing work from one hour.

So the our option A is correct.

A.fixed-interval

the answer should be demonstrations i hope this