读不懂正确选项跟文章有神马关系

bunnyfdu2015

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 ______.

	there are more fossilized mastodon remains from the period before mastodon populations began to decline than from after that period
	the average age at which mastodons from a given period reached reproductive maturity can be established from their fossilized remains
	it can be accurately estimated from fossilized remains when mastodons became extinct
	it is not known when humans first began hunting mastodons
	climate changes may have gradually reduced the food available to mastodons

选B，我知道其他几个太扯了，但实在搞不懂B哪里可以解释原文了？我自己做的时候选的C，艾玛下个月考试绝对要悲剧了。读不懂正确选项。。。