再问gwd10-1

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.

 我想选a

但是，是不是要考虑city 的被动语态