单选题 The passage suggests which of the following about air pollution?

A、 Further attempts to reduce emission from gasoline-fueled vehicles will not help lower urban air-pollution level.
B、 Attempts to reduce the pollutants that an individual gasoline-fueled vehicle emits have been largely unsuccessful.
C、 Few serious attempts have been made to reduce the amount of pollutants emitted by gasoline-fueled vehicles.
D、 Pollutants emitted by gasoline-fueled vehicles are not the most critical source of urban air pollution.

【正确答案】 A

【答案解析】这是一道暗示题。根据第一段可知，进一步减少汽车的尾气排放已不能解决城市污染问题。故此，答案为A。