Suppose the income tax rate is zero on the first $10,000; is 10% on the next $20,000; 20% on the next $20,000; 30% on the next $20,000; and 40% on all income above $70,000. Family A has income of $100,000 while Family B has income of $40,000. The marginal tax rate on the two families are

Select one:

a. 40% on A and 10% on B.

b. 30% on A and 20% on B.

c. 40% on A and 20% on B.

d. 30% on A and 30% on B.