Suppose the tax rate on the first $10,000 income is 0; 10 percent on the next $20,000; 20 percent on the next $20,000; 30 percent on the next $30,000; and 40 percent on any income over $80,000. Family A has income of $40,000 and Family B has income of $100,000. What is the marginal and average tax rate for each family? a. Family A: marginal20 percent; average10 percent; Family B: marginal40 percent; average23 percent. b. Family A: marginal20 percent; average15 percent; Family B: marginal40 percent; average20 percent. c. Family A: marginal10 percent; average10 percent; Family B: marginal30 percent; average30 percent. d. Family A: marginal20 percent; average20 percent; Family B: marginal40 percent; average40 percent.