Final answer:
Monica's emotional reactions to her therapist, which are similar to those she has towards her father, illustrate the psychological concept of 'stimulus generalization'.
Step-by-step explanation:
Monica's psychotherapist reminds her so much of her father that she has many of the same mixed emotional reactions to him that she has to her dad. Her reactions to her therapist best illustrate the importance of stimulus generalization. Stimulus generalization refers to demonstrating the conditioned response to stimuli that are similar to the conditioned stimulus. In this situation, the therapist is a new stimulus that resembles her father and evokes similar responses due to their similarity.