2.Cooperative apartment houses have the peculiar distinction of being dwellings that must also operate as businesses.
(A) of being dwellings that must also operate as businesses
(B) of dwellings that must also operate like business
(C) that they are dwellings that must operate like business
(D) that, as dwellings, they must also operate like businesses
(E) to be a dwelling that must also operate as a business

I would like to know the error in choice D...OA to follow