请教L2003-10-A-8

8. Vervet monkeys use different alarm calls to warn each other of nearby predators, depending on whether the danger comes from land or from the air.

which contribute most to explain the behavoir of the vervet monkeys?

Correct) Vervet monkeys avoid land-based predators by climbing trees but avoid prdation from theair by diving intofoliage.

why not C: ? C)No predators that pose a danger to vervet monkeys can attack both from land and from the air.

最后一句话，whether ...or , 是不是前后互相派除的,muturally exclusive, 即前后两种情况不能并存？

楼主大概没有理解题目的意思，其实是说v monkeys用不同的信号警示同伴，而这种不同是基于nearby predators也就是danger是来自陆地还是天上，这样是不是明白了。

btw,楼主什么时候考啊！现在准备得怎么样？