BarryLi wrote:Having often been thought of as still a city of working-class neighborhoods, Chicago is increasingly populated by poor people.

A) Having often been thought of as still a city of working-class neighborhoods, Chicago is increasingly populated by poor people.
Having often been thought = use of perfect participle, this is not required I think, perfect participle is used, when one action is ended and another action immediately follows that.
Having delivered the mail, the postman left.

B) It is still often thought of as a city of working-class neighborhoods, and Chicago is increasingly populated by poor people.
, and = coordinating conjunction, coordinating conjunction joins two standalone clauses, but in this case, these are not independent. It is thought that Chicago is a city of working class, BUT it is populated by poor.

C) In spite of still often being thought of as a city of working-class neighborhoods, the people who populate Chicago are increasingly poor.
Wrongly modifies the people.
D) It is still often thought of as a city of working-class neighborhoods, but the people who populate Chicago are increasingly poor.
Same as C, wrongly modifies people.
E) Although still often thought of as a city of working-class neighborhoods, Chicago is increasingly populated by poor people.
Correct.
OA: E