Every year for the past several decades, the total number of births in

Question

Every year for the past several decades, the total number of births in the combined rural areas of Baklavastan has been significantly lower than the total number of deaths in those same rural areas. Nevertheless, Baklavastan’s rural population has increased continuously over that same period.

Which of the following, if true, best explains the apparent paradox described in the passage?

(A) Baklavastan’s rural hospitals do not have neonatal intensive care units and offer only basic obstetric care, so rural mothers whose pregnancies are classified as higher-risk typically travel to urban hospitals, where neonatal ICUs and specialty obstetric care are available, to give birth.

(B) In recent years, a growing number of retirees from Baklavastan’s urban industries have moved out to the countryside upon retirement.

(C) The average age at death of Baklavastan's rural residents is almost five years greater than the corresponding figure for the urban population, in large part because of the cumulative toxic effects of increasingly dire urban pollution from industrial effluents and fossil-fuel emissions.

(D) For the past fifty years, Baklavastan’s government has steadily expanded its visa programs for highly skilled immigrants; as a result, the number of highly skilled workers who have immigrated to and settled permanently in Baklavastan has grown each decade for the past five decades.

(E) There are 2.8 children per adult woman in Baklavastan’s combined rural areas, but only 1.7 children per adult woman in its combined urban areas.

Vickynionog · Answer

B
Total number of people in rural places= existed population + birth - death
 because,  birth<death , total number increased
 so,  existed population must increase

(B)a growing number of retirees from Baklavastan’s urban industries have moved out to the countryside upon retirement.
 match.

karmachaser · Answer

B. Actually gives a reason why the rural population would still be increasing. Unlike the others.

A sounds tempting but it only gives an explanation as to why the birth rates are low.

C is irrelevant comparing rural to urban pop doesn’t address paradox

D doesn’t address rural population specifically

E is irrelevant

RonPurewal · Answer

Consider the timeframe of the phenomenon that needs explanation.

RonPurewal · Answer

If births and deaths were the only influences on Baklavastan’s rural population, the population would increase during periods when births exceed deaths, and would decrease during periods when deaths exceed births. However, the passage describes a population that has increased over a period during which there have been more deaths than births.

The only other possible influences on population—besides births and deaths—are immigration and emigration. SInce birth and death rates cannot possibly explain the steady increase in Baklavastan’s rural population, the required explanation MUST involve net movement of people from urban to rural areas.

Since we’re examining birth and death rates, the kind of “net movement” that matters here is of people who were born in rural areas but died in urban areas, or vice versa.
Which direction do we need? Well, we need to be able to explain a DEATH rate that’s greater than the birth rate—despite a growing population—so we can give quite a precise ‘template’ for the correct answer here:

WE NEED...
... a pattern in which people who were BORN in Baklavastan’s URBAN areas—or born OUTSIDE Baklavastan—MOVE TO (and eventually die in) its RURAL areas, WITHOUT a counterbalancing group of people who were born in rural Baklavastan but who move, and die, elsewhere.

Let’s evaluate the answer choices against this standard.

(A)
The babies of these mothers are born at urban hospitals—inflating the urban birth rate, and depressing the rural birth rate—but then “move” back to their rural family homes as soon as they leave the hospital. If this is indeed the case for MOST rural mothers with higher-risk pregnancies (= what they “typically” do), then the overall effect of these births on our aggregate statistics will definitely be non-negligible. Furthermore, since birthing services at Baklavastan’s rural hospitals are so much more limited than at its urban hospitals, there will be no counterbalancing population of urban mothers who travel out to rural hospitals to give birth—so this choice is exactly the explanation we need.

(B)
The net movement of these retirees is in the required direction, from urban to rural areas (where they’ll most likely be counted into the eventual death rate)—but this phenomenon has only occurred in “recent years”, so it cannot possibly explain the statistical trend described in the passage, which has been happening for several decades.

(C)
The effects of birth rates and death rates on overall population sizes are absolute; they are not affected in any way by the ages at which people die, so this choice is irrelevant.

(D)
If a steady pattern of international immigration into Baklavastan’s RURAL areas were described here, then this choice would potentially explain the paradox. However, there is nothing here to indicate that these immigrants settle in rural areas—which are certainly not a typical destination for SKILLED immigrant workers (who overwhelmingly find jobs in urban areas). So this choice is largely irrelevant.

(E)
This choice presents evidence that Baklavastan’s rural areas have substantially higher birth rates than its urban areas. This problem, however, is concerned only with the comparison between rural birth and death rates. The comparison between rural and urban birth rates is irrelevant.

Rishmadhu · Answer

Passage summary:
The total births in Baklavastan's rural areas have been significantly lower than the total deaths in those same rural areas.
Yet, the rural population has continuously increased.
Paradox:
Normally, if deaths exceed births in a place, population should shrink, not grow.
So, how can rural population increase despite more deaths than births?
What could explain it?
Other factors besides natural increase (births - deaths) affect population size, such as:

Migration into rural areas (people moving from urban areas or elsewhere)
Errors in data
Births counted elsewhere
Other demographic effects or classifications.
Analyzing each answer choice:
(A)

Rural hospitals lack neonatal intensive care, so high-risk pregnancies go to urban hospitals to give birth.
This implies births of rural mothers are recorded in urban areas, meaning rural births are under-counted in rural stats.
So actual babies born to rural residents may be higher; rural birth numbers are artificially low.
This can explain the paradox: births are happening, but recorded elsewhere.
This is a strong candidate.

(B)

Many retirees from urban industries move to the countryside after retirement.
Migration into rural areas would increase rural population.
This explains population increase even if births < deaths.
Also a good candidate.
(C)

Rural residents die older, because urban pollution causes earlier death.
This relates to mortality rates and health but does not address the population increase despite deaths exceeding births.
Doesn't explain the paradox directly.
(D)

Increased immigration into Baklavastan of highly skilled workers.
But nothing says they settle in rural areas.
Likely immigrants settle in urban areas for jobs, so unrelated.
(E)

Rural fertility rate: 2.8 children/woman
Urban fertility: 1.7 children/woman
If rural birth rate is high but the passage says births are significantly lower than deaths.
This is contradictory, so it does not explain why births are low in rural areas in their statistics.
Narrowed down options: (A) and (B)
Which explains the paradox best?
(A) Explains the paradox by pointing out statistical artifact: the births counted in rural areas are too low because rural women give birth in urban hospitals. So births are under-recorded in rural stats → explains why births recorded are less than deaths, yet population grows.

(B) Says retirees move into rural areas → migration raises population.

Both explain population increase despite births < deaths.

But the passage says:
"Births in rural areas are significantly lower than deaths in rural areas."
Population grows — why?
If births to rural residents are recorded in urban areas (A), the birth number for rural areas is correctly low, but not representative of births to rural residents.

If retirees move in (B), migration explains population growth even though natural increase is negative.

Which is more directly and completely explaining the paradox?
The paradox is about recorded births/deaths numbers in rural areas.

If rural births are recorded in urban areas, the "births in rural areas" number is artificially low, and the comparison to deaths is misleading.

Alternatively, (B) explains the actual population increase is due to in-migration.

GMAT logic preference:
The paradox deals with statistics on births vs deaths in rural areas, and population increase in rural areas.

If recorded rural births are low → apparent births < deaths — but actual births to rural residents are high. This directly solves the paradox by exposing a data classification or measurement issue.

Whereas (B) assumes data is correct but population increase is due to migration — but the question says "births" and "deaths" explicitly in those same rural areas, so (A)'s explanation that births are counted elsewhere logically fits better with how population can increase despite the stats.

RonPurewal · Answer

Rishmadhu, that's a correct explanation of why choice A is the correct answer. The biggest problem with choice B, though, is that the timeframe of the phenomenon described in choice B ("recent years"—a phrase whose ordinary use never goes back further than about a decade) is much too short to explain anything that's been happening for "the past several decades", as has the phenomenon in the passage.

The other thing that makes choice A airtight is that it describes a circumstance that definitely will NOT have a countering population going in the other direction. I.e., there will not be a comparable population of expectant mothers who live in Baklavastan's cities but will travel out to rural hospitals—which have  fewer  provisions for birthing mothers—to give birth; therefore, we can rest assured that there's no counter-trend to cancel out the trend in choice A.
By contrast, for choice B, there certainly *could* be a countering population of people who were born in Baklavastan's rural areas, but who move to cities at some point in their lives (which could be pretty much any stage of life between birth and death, since the statistics of interest are birth and death rates), e.g. for skilled employment. In fact, it's quite reasonable—even likely—that most of the retirees described in choice B were born and raised in the countryside to begin with (and wanted to go back home when they retired), in which case they would not cause any anomaly in the birth and death statistics in the first place.
You don't strictly  need  to consider choice B in this much depth, though, since you can eliminate B by just noticing that it describes something that hasn't been happening for as long as the thing you want to explain.

Every year for the past several decades, the total number of births in

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