Hi,
Please find below the official Solution:
UNDERSTANDING THE PASSAGE1. As per a survey:
a. an average middle-aged person drive 2000 miles a year and almost all of them own a gasoline-run car
b. Most of these middle-aged guys would switch their cars to electric ones, if the costs of making the switch are not high
2. The government of Papula is planning to implement a plan that would allow all the current owners of gasoline-run cars to switch to electric cars at a minimal cost.
UNDERSTANDING THE QUESTION STEMThe given question is a weaken question; however the conclusion is not stated in the passage but is given in the question stem. Basically, when we say that the conclusion is stated in the question stem, what we mean is that the statement that needs to be weakened is in the question stem.
The relevant conclusion is:
The plan, as envisaged by the government of Papula, will be able to significantly reduce the air pollution in the country in the next five years.
PRE-THINKINGThe author in this question makes predictions about the behavior of a population based on data from survey from a sample of the population – middle aged people. Hence, while making the prediction the author makes the assumption that the sample data must be representative of the population data or the preferences of the sample must be representative of the preferences of the majority.
One easy to spot weak point of the argument is that the plan of the government is based on the data of only middle-aged persons whereas the objective that needs to be achieved i.e. reduction in pollution will depend on other sections of population also. Besides, there is nothing to suggest in the passage that middle-aged population is responsible for a large proportion of the total pollution in the country. Thus, we can pre-think two weakeners for the given argument:
1. Any statement that suggests that other sections of population have preferences which are different from middle-aged population
2. Any statement that suggests that middle-aged population accounts for only a small proportion of the total population in the country
ANALYSIS OF ANSWER CHOICESA.
Though some of the citizens are concerned about the negative environmental impact of air pollution, they will not spend any extra money to protect the environment. – The success of the plan does not require each and every citizen to use the plan. There could be exceptions. This kind of answer choice is one of common type of incorrect choices used by GMAT in weaken question type.
Incorrect.B.
The budget deficit of the government of Papula is already at alarming levels, and any further increase in the deficit could lead to the bankruptcy of the country. – We are concerned with the impact of the plan on the pollution in the country. The impact the plan has on the financial status of the country is not the concern of the argument.
Incorrect.C.
Since Papula is an aging country, with more than half its population near retirement age, the chief consideration for a large number of its citizens is the convenience to drive rather than the costs to do so. – This statement actually captures both the weakeners that we came up with during the pre-thinking stage. It not only tells that a majority of population is not middle-aged, it also tells that the majority of population prefers convenience, something that the government has not taken into consideration while coming up with it’s plan.-. Therefore, this statement weakens the conclusion.
Correct.D.
In the last two decades, Papula has emerged as a major economic hub, leading to an increase in the living standard of its citizens and in the number of cars in the region. – This statement tell us that the number of cars have increased in the country. But as per the plan, these cars would be replaced with electric ones and once that is done, the pollution should decrease, doesn’t matter the number of cars. Therefore, this option doesn’t affect the conclusion.
Incorrect.E.
Since people who don’t own gasoline cars would not be benefitted from the proposed plan, they may strongly oppose the use of taxpayer money on such a plan. – Like option 2, this option also tries to cast a doubt on whether the plan can be implemented. However, within the context of the conclusion, we are not concerned about such a thing.
Incorrect.Hope this helps

Thanks,
Chiranjeev