(A) Incorrect.
The meaning of this statement is that
if roads are not widened, increases in traffic volume generally produce decreases in the average speed of traffic.
The statement presents a problem (a decrease in the average traffic speed, which might lead to a decrease in the effectiveness of air pollution control devices) with not widening the roads. By doing so, the statement supports the widening of the roads.
Thus, the statement is in the opposite direction of what we want. We want an option to indicate a problem with the widening of roads (specifically that the widening of roads will lead to an overall increase in air pollution).
We can, thus, rule out this option.
One may ask: does this option weaken the point mentioned in the last statement?
The answer is No.
The option indicates that with the widening of roads, increased traffic will not lead to a decrease in the average traffic speed. (However, the option doesn’t indicate that the widening of roads will lead to an increase in average traffic speed.)
If there is no decrease in the average traffic speed, there is no decrease in the effectiveness of air pollution control devices. In such a case, there will not be more pollution because of the reduced effectiveness of air pollution control devices.
However, the increased traffic due to wider roads (as given in the passage) is still expected to lead to more pollution. Thus, the point mentioned in the last statement is not weakened.
(B) Incorrect.
This option has no impact either on the statement by city officials or on the environmentalists’ concern.
The temporary closure of the roads doesn’t impact whether widened roads will lead to more pollution or less pollution.
(C) Correct.
This option says that most air pollution generated by urban vehicles comes from vehicles that do not have functioning pollution-control devices. If so, increased average speed due to widened roads will not help reduce pollution. If many vehicles do not even have these pollution-control devices in the first place, at what speeds they act at optimum levels becomes a moot point. Thus, we have a reason to believe that the increased air pollution due to more traffic will not be offset by a reduction in pollution due to better functioning pollution control devices.
(D) Incorrect.
Let’s first evaluate the following version of D:
D1: the newly widened roads will not have increased traffic volume
If D1 is the case, the environmentalists’ concern is weakened. Perhaps, there will not be much increase in pollution. Thus, we have a reason to believe that the reduction in pollution due to faster speeds will offset the increase in pollution due to more traffic (since there is not much increase in traffic).
Thus, this option is in the opposite direction of what we want.
Now, let’s get back to the original option D:
If the roads that must be used to reach them are inadequate, the newly widened roads will not have increased traffic volume
This option presents a specific situation in which the newly widened roads will not have increased traffic volume.
Which situation?
The situation in which the roads that are needed to reach the newly widened roads are inadequate.
So, if people don’t have a good way to reach the newly widened roads, these roads will not have increased traffic volume.
However, we don’t know whether this will be the case in city T. Besides, even if it is, the option suggests something opposite to what we want, as I explained above.
(E) Incorrect.
If such vehicles spend less time on the roads, we have a reason to believe that their average speed has increased and that there will be less pollution in T.
Thus, this option suggests a benefit of widened roads and is thus opposite to what we want.
