HBSDreamer2015 wrote:
Which of the following most logically completes the reasoning?
Either food scarcity or excessive hunting can threaten a population of animals. If the group faces food scarcity, individuals in the group will reach reproductive maturity later than otherwise. If the group faces excessive hunting, individuals that reach reproductive maturity earlier will come to predominate. Therefore, it should be possible to determine whether prehistoric mastodons became extinct because of food scarcity or human hunting, since there are fossilized mastodon remains from both before and after mastodon populations declined, and __________.
(A) there are more fossilized mastodon remains from the period before mastodon populations began to decline than from after that period
(B) the average age at which mastodons from a given period reach reproductive maturity can be established from their fossilized remains
(C) it can be accurately estimated from fossilized remains when mastodons became extinct
(D) it is not known when humans first began hunting mastodons
(E) climate changes may have gradually reduced the food available to mastodons
Official Guide for GMAT Verbal Review 2018Practice Question
Question No.: CR 130 KanikaG16Two reasons threaten animals - food scarcity or excessive hunting
If food scarcity, individuals in the group will reach reproductive maturity later than otherwise.
If excessive hunting, individuals that reach reproductive maturity earlier will predominate the group.
Therefore, it should be possible to determine whether prehistoric mastodons became extinct because of food scarcity or human hunting, since there are fossilized mastodon remains from both before and after mastodon populations declined, and ...The argument gives us two reasons that threaten and tells us how the group composition changes in either case.
It concludes that we should be able to determine what the reason was for extinction of mastodons - food scarcity or hunting.
The last part is supporting why we should be able to determine the reason. To determine the reason we would need to know whether after getting afflicted with the cause, the 'individuals in the group reached reproductive maturity later' or 'individuals that reached reproductive maturity earlier predominated'.
We are given that remains from before and after decline are available. Now to determine, we should be able to figure out the age at which they reached reproductive maturity. This is what (B) says:
(B) the average age at which mastodons from a given period reach reproductive maturity can be established from their fossilized remains
The last part now becomes:
... since there are fossilized mastodon remains from both before and after mastodon populations declined, and the average age at which mastodons from a given period reach reproductive maturity can be established from their fossilized remains.
Perfect. Now we can find out the reason for extinction.
Answer (B)