Answer:.b. stimulus control.
Step-by-step explanation:
According to behavioral psychology, stimulus control refers to how an organism tend to change their behavior in the presence of a certain stimuli and return to another behavior in the absence of that stimuli.
Someone uses discriminative stimulus to refine their behaviour in response to a particular stimuli such as when Robert sees the police officer this is a behavior driven by knowing that this is an authority figure and is based on historical reinforcement.