请教一道简单语法题

ying777

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.



A.so stalking them over the treeless landscape, getting close enough to kill it

B.so to stalk them over the treeless landscape and get close enough to kill one

C.so in order to stalk them over the treeless landscape and get close enough to kill one

D.and so in order to stalk it over the treeless landscape, getting close enough to kill it

E.and so stalking them over the treeless landscape and getting close enough in order to kill it
请教NN，为什么答案是B 不是A呢？

AmyGMAT

to do强调目的性动作，在这里更符合题目想要表达的意思，为了..所以需要..
A中it没有指代对象，前面的caribou是复数名词
并且A中getting前面应该去掉逗号加and，连接两个一起做主语的动作