Which of the following best illustrates an operating expense included in an income statement?

The correct answer highlights that operating expenses are the costs required to run a company's core business operations on a day-to-day basis. Cost of goods sold (COGS) directly relates to the production of goods sold by a company and is classified as an operating expense because it reflects the direct costs associated with manufacturing the products or providing services that generate revenue.

Operating expenses are essential for running the business and include items such as rent, utilities, salaries, and raw materials that contribute to the production of goods sold. Since COGS falls into this category as it accounts for the costs that are directly tied to production and sales, it is indeed classified under operating expenses in the income statement.

In contrast, interest income refers to earnings generated from investments or financial assets and is not an operating expense but rather part of a company's non-operating income. Sales revenue represents the total income generated from goods or services sold and does not classify as an expense. Income tax expenses are associated with the taxation of profits, which, while a crucial component of net income, is categorized separately from operating expenses on the income statement.