Melissa engages in an activity that influences the well-being of a bystander. In order for Melissa’s activity to give rise to an externality, it must be the case that (             ).
A、Melissa fails to recognize the impact of her activity on the bystander’s well­being
B、the bystander fails to recognize the impact of Melissa’s activity on his or her well­being
C、the well­being of the bystander is adversely impacted by Melissa’s activity
D、Melissa neither pays nor receives any compensation for her activity