再问一道逻辑题．．

gmatziyu

ｐｒｅｐ逻辑请教
When people evade income taxes by not declaring taxable income, a vicious cycle results.Tax evasion forces lawmakers to raise income tax rates, which causes the tax burden on nonevading taxpayers to become heavier.This, in turn, encourages even more taxpayers to evade income taxes by hiding taxable income.



The vicious cycle described above could not result unless which of the following were true?



(A) An increase in tax rates tends to function as an incentive for taxpayers to try to increase their pretax incomes.

(B) Some methods for detecting tax evaders, and thus recovering some tax revenue lost through evasion, bring in more than they cost, but their success rate varies from year to year.

(C) When lawmakers establish income tax rates in order to generate a certain level of revenue, they do not allow adequately for revenue that will be lost through evasion.

(D) No one who routinely hides some taxable income can be induced by a lowering of tax rates to stop hiding such income unless fines for evaders are raised at the same time.

(E) Taxpayers do not differ from each other with respect to the rate of taxation that will cause them to evade taxes.
请问这题为什么选ｃ呢？
谢谢！

dphxmg

The vicious cycle: tax evasion--> increase in tax rates --> more tax evasion
Question: What is necessary to maintain the cycle?

A) breaks the cycle, because increase in tax rates --> people would work harder than they do before.
B) would strengthen the cycle to some extent but is not necessary.
C) is correct. Because we negative it, the cycle will be cut off. If govmnt allows for tax evasion beforehand, it does not need to increase tax rates.
D) is out of scope, because it is about lowering of tax rates.
If E) is correct, either no one evade tax, or everybody pays tax. In either case, there won't be the vicious cycle.

gmatziyu