Sentence Correction

226. 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


Is businessess is a correct word? why is the answer A

Subject in this case is "Cooperative apartment houses", a plural, so Option A or D.
And "D" violates the original meaning in sentence, hence "A".