（1）    
GWD-30-Q2

Caribou are wary
animals with excellent hearing, so stalking them over the treeless
landscape, getting close enough to kill it with nothing but a handheld
lance, as Dorset people did, required
exceptional hunting skill.

1. so
        stalking them over the treeless landscape, getting close enough to kill it
2. so to
        stalk them over the treeless landscape and get close enough to kill one
3. so in order
        to stalk them over the treeless landscape and get close enough to kill one
4. and so in
        order to stalk it over the treeless landscape, getting close enough to
        kill it
5. and so
        stalking them over the treeless landscape and getting close enough in
        order to kill it

刚查了字典so可以作为连词，字典上给出的例子:So that's how I first met your mother.

然后我觉得one在这里有强调的意思，题目的意思是c是一种很警觉的动物并且听力很好，想要抓到“一只”都不是一件容易的事情，需要出色的hunting skill

答案是B吗？

so 當連詞應在og 出現過, 而且還滿常用的:

conj. (連接詞 conjunction)

1.       因此,所以

The manager was ill so I went in her place.

經理病了所以我代她去。

2.       因而,從而

Mom told him to go to bed early so he could get up early the next morning.

媽媽叫他早點上床睡覺,第二天早上好早點起床。

THANKS