Answer:The act of holding the door is reinforced on a VARIABLE-RATIO reinforcement schedule.
Explanation:
In operant conditioning, a variable-ratio schedule refers to a reinforcement in which the action is carried out for a long period of time after which a response is then reinforced.
An example is playing lottery one keeps playing a multiple times before they receive a response.
The frequency of a behaviour will determine how fast a response can be obtained and how strong it will be.
