Final answer:
The power structure described in the question is centralized.
Step-by-step explanation:
The type of power structure described in the question is centralized. In a centralized power structure, decision-making authority is concentrated at the top of the organization, with key decisions being made by the manager or a small group of individuals. In this case, the head chef, dining room supervisor, and lead hostess require the approval of the restaurant manager, indicating that decisions that impact guests are centralized and require the manager's input.