GWD-9-Q20

saharaa

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 reached 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

queenie924

同问同问，这道题什么意思啊？如何选出B的呢？哪位好心的NN给各解释 ！

tania_zhang

food scarcity会导致reproductive maturity later
excessive hunting会导致reproductive maturity earlier
也就是说reproductive maturity可以判断灭绝原因
而it should be possible 直到灭绝的原因是food scarcity或者excessive hunting，也就是说可以判断出reproductive maturity的早晚，也就是B选项

queenie924

谢谢2楼！想再请问前面那个原因是什么意思，想表达什么呢？（就是紧接着since那个）

tania_zhang

since there are fossilized mastodon remains from both before and after mastodon populations declined
有在m的数量减少时前后时期的化石

就是通过比较数量减少前、减少后时m的成熟期的早晚来比较，m数量减少后，成熟期是变早还是晚了，来推断出灭绝的原因。

tania_zhang

十分感谢 ！！！