had tranformed Vs was tranformed

Question

Tom Bradley was mayor of Los Angeles from 1973 to 1993, an era when the city had transformed from a collection of suburban neighborhoods to the second-largest city in the United States.
A. an era when the city had transformed
B. an era during which the city was transformed
C. an era that transformed it
D. during which era the city transformed
E. during which the city was transformed

In the above problem:
C: IT is wrong.... era is not transforming
D: during which era is wrong

Now coming to A and B.... "HAD TRANSFORMED" Vs "WAS TRANSFORMED"
Do we need to use Had transformed... because we are talking of the things or changes happening in that period 1973 to 1993?...
Anyone Please explain.. i feel there can be a GENERAL RULE for all these kind of problems which describe the events happening at a certain time period thanks...

killer1387 · Answer

Tom Bradley was mayor of Los Angeles from 1973 to 1993, an era when the city had transformed from a collection of suburban neighborhoods to the second-largest city in the United States.

A. an era when the city had transformed
--> use of HAD makes the meaning ambiguous

B. an era during which the city was transformed
--> correct

C. an era that transformed it
--> era cant transform

D. during which era the city transformed
E. during which the city was transformed
--> An era is required to concrete the meaning of the sentence. Hence D/E out.

nandy1984 · Answer

killer1387 wrote:Tom Bradley was mayor of Los Angeles from 1973 to 1993, an era when the city had transformed from a collection of suburban neighborhoods to the second-largest city in the United States.

A. an era when the city had transformed
--> use of HAD makes the meaning ambiguous

B. an era during which the city was transformed
--> correct

C. an era that transformed it
--> era cant transform

D. during which era the city transformed
E. during which the city was transformed
--> An era is required to concrete the meaning of the sentence. Hence D/E out.

Hi my question here is not with other options my question is with "HAD transformed" and "was transformed"... it will help if you can explain it when to use rather than saying ambiguous... I want to understand this not only for this problem, but also for future problem of similar kind... thank you

vikram4689 · Answer

You will use "was transformed" because we are talking of a PAST EVENT in PRESENT. "had transformed" would have been correct if we talk of PAST EVENT in PAST TENSE.

E.g. Before i became a teenager, i had won 4 gold medals in soccer.

Here i won (in past) before i became teenager (another past event).

Let me know if this helps

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Bill@VeritasPrep · Answer

To me, "had transformed" almost makes it sound like the city transformed itself, while "was transformed" makes it clear there were outside forces. Although maybe LA is one giant Transformer

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had tranformed Vs was tranformed

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