Industrialisation and modern methods of insect control

[vid]

Industrialisation 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

By POE, I am able to arrive at the correct OA B.
My doubt is , how can the subordinate clause starting with 'while' in B not have a finite verb.
To my knowledge, a clause should have a finite verb.Here introducing is a participle(infinite).

Pls explain grammar.

[hedonist]

Industrialisation 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

By POE, I am able to arrive at the correct OA B.
My doubt is , how can the subordinate clause starting with 'while' in B not have a finite verb.
To my knowledge, a clause should have a finite verb.Here introducing is a participle(infinite).

Pls explain grammar.

How did we eliminate D? I was unable to choose one between B and D.

[dbernst]

Vid, it is grammatically acceptable to state "they have improved X while introducing Y." Answer choice D, however, by utilizing the coordinating cunjunction "but," creates a provable tense error. In essence, choice D is stating, "They have improved X but introducing Y." In this construction, the past tense "introduced" would be necessary.

-dan

[georgy]

:cool: sdfs

[GEORGY]

FOLLOWING ALSO COULD BE A REASON
'HAVING GONE ' IS A PERFECT PARTICIPLE,USED IN PASSIVE VOICE & PASSIVE VOICE IN UNPOPULAR WITH GMAT

What is the perfect participle?

The perfect participle indicates completed action. You form the perfect participle by putting the present participle having in front of the past participle.

For example:-

having done, having finished, having read, having spoken

It can be used to form the passive voice.

For example:-

Having improved her English Pia's promotion prospects were much better.

[RonPurewal]

http://www.manhattangmat.com/forums/ind ... -t460.html

if any questions remain unanswered, please append them onto the linked thread.
thanks.