Among the following items, the one that should be included in the "operating income" item of the income statement is ().

Answer: A

The "operating income" item of the income statement reflects the inflow of economic benefits formed in the daily activities of the enterprise, including main business income and other business income accounts. Income from the sale of materials should be included in "other business income" and included in the "operating income" item of the income statement. Cash received from donations, net income from the sale of patent rights, and net income from the sale of self-used real estate should be included in "non-operating income" and should not be included in the "operating income" item of the income statement.