The correct answers are C. Interest expense and D. Cost of goods sold. Net income is determined by starting with revenues and then subtracting expenses and other costs. Because interest expense is an expense, increasing it reduces earnings before tax and therefore lowers net income. Likewise, cost of goods sold (COGS) is a major expense directly tied to the goods sold by the business. When COGS increases, gross profit falls, which then reduces net income. OpenStax summarizes the income statement as including revenues, expenses, gains, and losses in arriving at net income or net loss.

Options A. Gains and B. Revenues are incorrect because increases in either of those items generally increase net income rather than decrease it. Gains arise from peripheral transactions and still improve profitability, while revenues represent inflows from the company's main operations. In contrast, both interest expense and cost of goods sold are deductions in the income statement. Therefore, the two items that decrease net income when increased are Interest expense and Cost of goods sold.