Final answer:
First-order change in the Family Systems Model is about modifying behavior patterns without significantly changing the underlying structures and functioning patterns of the family system option (c).
Step-by-step explanation:
In the Family Systems Model, the definition of First-Order Change refers to C: Modifying behavior patterns without altering substantially the basic structures and functioning patterns of the system. This type of change is often superficial and temporary, addressing only the immediate and apparent issues without transforming the underlying structure of the family system.
It's a way to resolve problems but does not lead to fundamental changes in how the family operates. It contrasts with second-order changes which are transformations that restructure the family system and alter its rules and interactions in a more profound and lasting manner.