prep question

It is a discrepency related CR .....you have to show that why inspite of having higher per capita income, Bahlton has half of its population living below poverty line....now in case of averages two things are possible.
One is Bahlton has rich people comapared to Kuptala which would compensate for half of the popultaion living in high poverty or the the income of people living in Kuptala i near to the average which is given in E.
In fact, there is a similar kind of question in Kaplan Verbal Workbook,but the answer in that question is the first reason...

Demographers doing research for an international economics newsletter claim that the average per capita income in the country of Kuptala is substantially lower than that in the country of Bahlton. They also claim, however, that whereas poverty is relatively rare in Kuptala, over half the population of Bahlton lives in extreme poverty. At least one of the demographers’ claims must, therefore, be wrong.
The argument above is most vulnerable to which of the following criticisms?
(A) It rejects an empirical claim about the average per capita incomes in the two countries without making any attempt to discredit that claim by offering additional economic evidence.
(B) It treats the vague term “poverty” as though it had a precise and universally accepted meaning.
(C) It overlooks the possibility that the number of people in the two countries who live in poverty could be the same even though the percentages of the two populations that live in poverty differ markedly.
(D) It fails to show that wealth and poverty have the same social significance in Kuptala as in Bahlton.
(E) It does not consider the possibility that incomes in Kuptala, unlike those in Bahlton, might all be very close to the country’s average per capita income.

the OA is E
i chose C..

The official answer is E. But I don't understand why? Can anyone explain