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
This question is based on Construction.
The conjunction ‘while’ is used to convey the meaning of ‘at the same time as’. The conjunction ‘but’ conveys a contradiction.
“Introduced” is not a verb but a participle.
The sentence conveys the idea that two things, albeit slightly contradictory, happened together. So, the conjunction ‘while’ is more appropriate than the conjunction ‘but’. Furthermore, the conjunction ‘but’ cannot be followed by a participle. There should be a verb after the conjunction. Since there is no verb after the conjunction in either of the options, D and E can be eliminated.
Option A has a participle modifier at the end. A participle modifier after a comma modifies the subject of the clause before it. So, the modifier modifies the pronoun ‘they’, which refers to “industrialization and modern methods of insect control” but it is not industrialization and methods of insect control that have gone unregulated. Since the meaning conveyed is illogical, Option A can be eliminated.
The modifier at the end of this option begins with the relative pronoun ‘which’. A relative pronoun refers to the noun placed immediately before it; in this sentence, the noun is ‘time’. Since it is not ‘time’ that has gone unregulated, the meaning conveyed by the placement of the modifier is illogical, and so, Option C can be eliminated.
Option B has the appropriate conjunction ‘while’, followed by the participle ‘introducing’; this option maintains the appropriate structure of the sentence to convey the idea that two actions – improving the standard of living and introducing dangerous pollutants – happened together.
I and M methods have improved the standard of living while introducing some dangerous pollutants.
The modifier “that have gone unregulated…..” appropriately modifies “chemical pollutants”. Therefore, B is the most appropriate option.