Final answer:
The U.S. Internal Revenue Service's focus on individuals, small businesses, corporations, and non-profit and government agencies represents a functional structure.
Step-by-step explanation:
The organizational structure represented by the U.S. Internal Revenue Service's focus on individuals, small businesses, corporations, and non-profit and government agencies is known as a "functional structure." In a functional structure, an organization is divided into departments based on the functions they perform.
Each department focuses on a specific set of tasks or objectives. In this case, the IRS has organized itself to efficiently handle the tax-related needs of different groups of taxpayers.