Answer:
Variable interval
Explanation:
Variable interval is one of method that people can use to give a certain reinforcement (punishment or reward) . The reinforcement will be given in a uncertain timing so the subjects will have no idea when the reinforcement will be given.
This can be seen in situation above.
The DJ said , "Sometime this hour, I'll be giving away a pair of tickets to the Ariana Grande concert to one lucky caller."
He did not give a specific time to give the reward (in this case, the ticket is considered as the reinforcement)
