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

(A) Fixed interval

Explanation:

 The fixed interval schedule is the type of schedule of the reinforcement in the operand conditioning in which the the initial response are rewarded by some specific amount of the time.

The main issue with the fixed interval schedule is that the people have to wait until the reinforcement schedule get occur and start their actual response of interval. This type of reinforcement schedule occur as the output value does not posses constant value all the time.

Therefore, Option (A) is correct.