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 LACE w:st="on">DorsetLACE> 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

觉得B选项比较好，但是还是不是很清楚这里to和in order to的区别，是不是这里是不定式做主语，而in order to没有这种用法？

to do sth. 可以作为主语，也可以作为前一个动作的后续（目的，补语）

in order to do sth. 只能作为状语，表示前一个动作的目的，不能用作主语。