Final answer:
All options provided—resistance, sequencing/timing, and interrupting past patterns—are key concepts in family therapy, contributing to its holistic approach to resolving familial issues.
Step-by-step explanation:
The key concept in family therapy is D. All of the above. Family therapy encompasses a range of concepts and strategies including A. Resistance, which involves recognizing and dealing with the reluctance or opposition that family members might express towards therapeutic interventions. Another concept is B. Sequencing/timing, which refers to the importance of understanding and utilizing the timing of interventions within the therapy process. Lastly, C. Interrupting past patterns is also central to family therapy, as it aims to identify and disrupt dysfunctional patterns of behavior and interaction that have been established within the family structure.