一道新题. 能解释一下原因吗

jnlvo

个人观点是B，不过解释跟9楼有所不同，赞同楼上给出的逻辑关系。

A. 本文只给了个前提条件increase agricultural production without reducing biodiversity, 这里reduce production和increase biodiversity的关系如何，跟本文推论应该是无太大关系.

B.由economic growth, which requires increasing agricultural production(A require B等价A→B),这样economic growth→increasing agricultural production

把B取反，Economic growth should be pursued at the expense of a loss of biodiveristy，换句话at the expense of a loss of biodiveristy是Economic growth的必要条件：economic growth→at the expense of a loss of biodiveristy，这样结合上面的推论就会有increasing agricultural production at the expense of a loss of biodiveristy这和推论的前提条件increase agricultural production without reducing biodiversity矛盾，所以B helps to justify the agricultural economist's reasoning

C.几乎是文中economic growth, which requires increasing agricultural production的等价说法，对文中的reasoning不起额外的作用。

D.important无关

E.extent无关

BTW, 这种题涉及充分必要条件，现在Gmat中较少涉及。个人觉得甚至不知道也没关系。