Official Explanation
The argument concludes that the increase in the prices of products because of an increase in the sales tax rate will not adversely affect the consumers because their salaries will also increase due to the abolition of income tax. However, what if this increase in the prices of products was much more than the increase in people’s salary? Then the situation will negatively impact the people. The argument obviously assumes this will not be the case. B states this and so strengthens the argument.
(A) The situation in European countries has no bearing on the situation in the US.
(B) The correct answer.
(C) This is an additional point and not relevant to the reasoning provided in the argument.
(D) Other taxes are outside the purview of the argument.
(E) The question is not whether the government will be able to bear the shock of abolition of income tax but whether such a move will be beneficial for the people.