单选题 Under current federal law, employers are allowed to offer their employees free parking spaces as a tax-free benefit, but they can offer employees only up to $180 per year as a taxfree benefit for using mass transit. The government could significantly increase mass transit ridership by raising the limit of this benefit to meet commuters" transportation costs. The proposal above to increase mass transit ridership assumes that

A、 current mass transit systems are subject to unexpected route closings and delays
B、 using mass transit creates less air pollution per person than using a private automobile
C、 the parking spaces offered by employers as tax-free benefits can be worth as much as $2,500 per year
D、 many employees are deterred by financial considerations from using mass transit to commute to their places of employment
E、 because of traffic congestion on major commuter routes, it is often faster to travel to one"s place of employment by means of mass transit than by private automobile

【正确答案】 D

【答案解析】[解析] 本题读题重点为段落最后一句话，且本题为“提出一方法来实现某个目的”，即通过提高津贴，可以增加公共交通的乘客数量。而选项(D)说明出于费用考虑(没有提高津贴)，许多人没有使用公共交通工具上班符合“无因就无果”的思路，所以(D)正确；(C)与“ridership”无关；(E)是一个无关比较，所以也不正确。