Senator Willie Mays, who retired as a player for the San Francisco Giants, proposes that income tax structure be revised to have two tax rates. The first tax rate, 25 percent, applies to persons whose income is between $0 and $50,000 a year. The second, 10 percent, applies to persons whose income is more than $50,000 a year. This is a

a. regressive income tax structure.

b. proportional income tax structure.

c. progressive income tax structure.

d. cyclical income tax structure