Answer:
a. self-fulfilling prophecy
Step-by-step explanation:
In psychology, a self-fulfilling prophecy refers to the phenomenon where someone "predicts" or expects something, and this “prediction” or expectation comes true simply because one believes it will, and therefore the resulting behaviors align to fulfil those beliefs. In other words, a false expectation leads to its own confirmation, so the false expectations of a person eventually lead the other person to behave in such way that it confirms the original expectations.
In this example Marion thinks Peter is unfriendly and she never says hello. Peter is shy and doesn't say hi either. This lack of greeting reinforces Marion's belief that he is unfriendly. We can see that Marion has a false expectation about Peter (he is unfriendly) and since she doesn't say hi, he doesn't say hi either, therefore, this leads Marion to "confirm" that Peter is unfriendly since the behavior of him not saying 'hi' align to fulfill this belief. Therefore, this is an example of self-fulfilling prophecy.