Answer: the partial reinforcement effect.
Explanation: Sim's persistence is most likely an example of the partial reinforcement effect. Reinforcement refers to the process whereby a behavior comes to be repeated. It refers to stimulus which strengthens or increases the probability of a specific response. Partial reinforcement is a type of reinforcement that only reinforced at certain intervals or ratio of time. Learned behaviors acquired from this form of scheduling as displayed by Sim, have been found to be more resilient to extinction.