Which of the following best describes the calculation of a business's gross income? a. Gross income is calculated by adding up all revenue received within a tax year, including returns, allowances, and the cost of goods sold. b. Gross income is calculated as gross receipts plus returns and allowances, and the cost of goods sold. c. Gross income equals the sum of rental income, interest and dividends, and the proceeds from the sale of capital assets. d. Gross income is calculated as gross receipts minus returns and allowances, and the cost of goods sold