[原创]一个PREP语法题目答案的商榷

B选项中的introducing是否因为没有交代该动作的发起者，不如选项C更好呢？

Industrialization and modern methods of insect control have improved the standard of living around the globe while at the same time they have introduced some 100,000 dangerous chemical pollutants, having gone virtually unregulated since they were developed more than 50 years ago.

(A) while at the same time they have introduced some 100,000 dangerous chemical pollutants, having
(B) while at the same time introducing some 100,000 dangerous chemical pollutants that have
(C) while they have introduced some 100,000 dangerous chemical pollutants at the same time,
which have
(D) but introducing some 100,000 dangerous chemical pollutants at the same time that have
(E) but at the same time introducing some 100,000 dangerous chemical pollutants, having

固定用法

while + doing something

主语为主句逻辑主语