What relates to a company's main business of selling products or services to earn net income?

The correct answer focuses on operating activities, which are directly linked to a company's core functions of generating revenue through the sale of products or services. These activities encompass the primary operations of a business, including sales revenue, cost of goods sold, and all expenses associated with production and delivery.

Operating activities are critical in assessing a company's ability to generate cash flow from its typical business operations, which directly contributes to net income. This aspect is central to understanding a company's financial health and sustainability over the long term.

While investing and financing activities are important components of overall financial analysis, they relate to different aspects of a company's financial management. Investing activities involve the acquisition and disposal of long-term assets, and financing activities pertain to how a company raises capital and manages its debts. Cost of goods sold captures the direct costs attributable to the production of goods sold, but does not encompass the entire scope of operating activities, which include all revenues and expenses generated from regular business operations.