Comprehensive and Detailed in Depth Explanation:

A hierarchical organizational structure is a pyramid-shaped model where the number of employees decreases as responsibility increases. At the top are a few executives with high responsibility, while the base has many employees with less responsibility.

Option A (Flat): A flat structure has few levels of management, with more employees reporting to each manager.

Option B (Matrix): A matrix structure combines functional and project-based reporting, not necessarily pyramid-shaped.

Option C (Regional): This refers to a structure based on geographic regions, not responsibility levels.