What type of income does operating income exclude?

Operating income specifically refers to the income generated from a company's main business operations, excluding certain elements that do not directly relate to its core activities.

The correct answer highlights that operating income excludes interest and taxes. This is essential because interest expenses and income taxes are not considered part of the operational effectiveness of the company. Instead, they are financial and regulatory costs that apply after the determination of operating income.

By focusing solely on operating income, one can assess how well the company performs in its primary business areas, without the distortions that can be introduced by financial structuring (interest) or governmental obligations (taxes). This allows for a clearer evaluation of operational efficiency and profitability based purely on regular business activities.

In contrast, other choices could potentially include elements that may or may not pertain to the core operations of the business. For instance, revenue from investments can affect net income but does not contribute to operating income, which is strictly tied to the company's main revenue-generating activities.