[求助] 蓝皮书 - GMAT 精选练习题（假定题）- 12 （第287页）

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 non-evading 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．

这道题没做对的原因是没读懂（C）选项，特别是句子的后半部分。有没有高手可以帮忙解答一下为什么这道题的正确答案是（C）？

C的意思是当L制定Rate的时候，没有因为事先考虑到evasion而多收入revenue

如果这个假设不成立  即L制定rate的时候留有余地 那么也就没有上面说的恶性循环了