Over the course of many years, the authorities in New York disabled mo

D is perfect, conveys intended meaning correctly, begins with the subject after comma and follows the "ing" format

Can any one please explain why A is wrong? I am confused between A and D.
Thank you.

Nothing, really wrong with but pronoun ambiguity issue seems to hinder. "They " is far from the "authorities", whereas the sentence still has few plural antecedents.

Simple answer: A isn't wrong. There's nothing unclear about "they," and the use of past perfect ("had") is justified. Sometimes folks trying to write their own questions will rely on simple applications of rules that don't really create clear splits of right and wrong.
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A. the authorities in New York disabled most of the control buttons that had once operated pedestrian-crossing lights in the city after they observed
Will come back to this choice later.

B. the authorities in New York had disabled most of the control buttons that once operated pedestrian-crossing lights in the city after observing
had is wrong

C. most of the control buttons that once operated lights at pedestrian-crossing in the city were disabled after the authorities in New York had observed
after-had doesn't make sense.
a) After observing -- okay
b) after had observed -- wrong.

D. the authorities in New York disabled most of the control buttons that once operated pedestrian-crossing lights in the city after observing
Will come back to this choice later.

E. most of the control buttons operating pedestrian-crossing lights in the city are being disabled since the New York authorities observed
wrong usage of being


Between A and D
A is wrong becuase meaning wise its wrong. It states that authorities disabled most of the controls that had once operated. If the buttons already stopped working, what was the need to disable them? Lol

Split 1: 'the authorities' vs 'most of the control buttons'- subject after the modifier
If we go with 'the authorities', we end up with a sentence that is active over sentences in option C & E- which are passive.

Split 2: 'Had once operated' vs 'once operated'
We don't need the past perfect tense here since the government did not disable buttons that were already out of use. Simple past is the right tense because the events were happening simultaneously. Option A and B are out.

Option D is the best one.

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