Which statement regarding the calculation of taxes is accurate? Answer: A. For simplicity, taxable income for federal income tax and Social Security tax has been standardized. B. All taxes are calculated based on net pay. C. Because retirement plans are exempt from federal income tax, you add the contributed amount before calculating the employee's federal withholding. D. Taxes may be calculated based on an amount lower than gross pay, and not all taxes are calculated based on the same amount