Which type of income includes earnings from secondary activities?

The type of income that includes earnings from secondary activities is known as non-operating income. This category encompasses revenue that is not generated through the primary operations of a business, such as interest earned from investments, gains from the sale of assets, or revenue from side projects and ventures that are not directly related to the core business activities.

Understanding the distinction between non-operating income and other types of income is crucial. For instance, operating income focuses specifically on revenue from core business operations, reflecting the profitability of the primary business activities without including any peripheral earnings. On the other hand, net income represents the overall profitability after all expenses, including both operational and non-operational factors, have been deducted. Gross income, similarly, refers to the total income before deductions, which includes revenues from all sources but doesn't isolate secondary activities from main operations.

In summary, non-operating income specifically captures earnings derived from secondary activities, making it the correct choice in this context.