Final answer:
To assess the roles and power structure of a client's nuclear family, the nurse should ask who decides where to go on vacation.
Step-by-step explanation:
The question is discussing the roles and power structure within a client's nuclear family. In order to assess this, the nurse should specifically ask the client questions that can help determine decision-making and power dynamics within the family. Out of the options provided, the most relevant question would be: 1. Who decides where to go on vacation? This question can provide insight into how decisions are made within the family and who holds the power in terms of making choices and planning activities.