Sentence Correction

A 2009 study from the California State Housing Authority concluded that conversion from ownership to rental properties has often been difficult; it has been more common for some townhouses and other "attached" homes that are relatively small and old, located in central cities.

A difficult; it has been more common for some townhouses and other "attached" homes that are relatively small and old, located in central cities.
B difficult; it has been more common for some townhouses and other "attached" homes that are relatively small, old, and that are located in central cities.
C difficult; it has been more common for some townhouses and other "attached" homes, which are relatively small and old, and located in central cities.
D difficult: It has been more common for some townhouses and other "attached" homes that are relatively small and old and located in central cities.
E difficult: It has been more common for some townhouses and other "attached" homes that are relatively small and old, and located in central cities.

OA - d

which is qualifying the homes , in c

e- comma before and is avoidable in gmat

a - last modifier is hanging
b - ...