Answer: Variable-Ratio
Step-by-step explanation:
The variable-ratio schedule is one of the type of reinforcement schedule in the operant conditioning in which the various types of unpredictable variables of the response are developed by the organisms.
The lottery and the various types of gambling games are the best examples of the variable-ratio schedule.
The main benefits of the variable-ratio schedule is that it creating the steady and the very high rating response in this type of reinforcement schedule.
Therefore, Variable-Ratio is the correct answer.