Final answer:
The nurse should identify the dysfunctional behavior as manipulation.
Step-by-step explanation:
The nurse should identify the adolescent son's behavior as manipulation. Manipulation is a dysfunctional behavior where someone uses deceitful or dishonest tactics to gain an advantage or control over a situation or other people. In this case, the son is trying to make his sister look bad to manipulate his parents into thinking he is the better sibling and therefore deserving of more privileges.