Compared to regular automobile fuel, low-sulfur automobile fuel produces a lower volume of harmful emissions such as sulfur oxides. In an attempt to improve the air quality in Litania, the Litanian government has cut the excise tax on low-sulfur fuel to a point well below that of regular fuel. Since automobiles perform equally well with either fuel, the government hopes that such a tax cut will encourage drivers to switch from regular fuel to the less polluting low-sulfur fuel.
Which of the following, if true, would most seriously call into question the Litanian government's plan to use this tax cut to improve air quality?
A. Automobile fuel is not the sole source of sulfur oxides in the atmosphere.
B. In terms of sulfur oxide emissions, the air quality of Litania is not as bad as the air quality of neighboring countries.
C. Some drivers in Litania are unaware of the availability of low-sulfur fuel as an alternative to regular fuel.
D. The cut in the excise tax for low-sulfur fuel is large enough to encourage significantly greater automobile use.
E. Many Litanian drivers remain unconvinced that automobile emissions are a significant threat to air quality.