Social Security and Medicare (HI) benefits are primarily financed by: a. a FICA tax of 1.45% up to $106,800. b. 6.2% tax on earnings to $168,600 and 1.45% on all earnings, paid by employer and employee. c. a flat tax of 15% on corporate income. d. FICA taxes of 15%, 28%, or 33% based on adjusted gross income