Which of the following best completes the passage below?
One tax-reform proposal that has gained increasing support in recent years is the flat tax, which would impose a uniform tax rate on incomes at every level. Opponents of the flat tax say that a progressive tax system, which levies a higher rate of taxes on higher-income taxpayers, is fairer, placing the greater burden on those better able to bear it. However, the present crazy quilt of tax deductions, exemptions, credits, and loopholes benefits primarily the high-income taxpayer, who is consequently able to reduce his or her effective tax rate, often to a level below that paid by the lower-income taxpayer. Therefore, ______
(A) higher-income taxpayers are likely to lend their support to the flat-tax proposal now being considered by Congress
(B) a flat-tax system that allowed no deductions or exemptions would substantially increase actual government revenues
(C) the lower-income taxpayer might well be penalized by the institution of a flat-tax system in this country
(D) the progressive nature of our present tax system is more illusory than real
(E) the flat tax would actually be fairer to the lower-income taxpayer than any progressive tax system could be


OA is D. I can't figure out why. Someone please expalin.