这道题是新东方语法教程（蓝色封面）里的句子对称和平行结构里的第二题
While the owner of a condominium apartment has free and clear title to the dwelling, owners of cooperative apartments have shares in a corporation that owns a building and leases apartments to them.
A. While the owner of a condominium apartment has free and clear title to the dwelling,
B. The owner of a condominium apartment has free and clear title to the dwelling, but
C. Whereas owners of condominium apartments have free and clear title to their dwelings,
D. An owner of a condominium apartment has free and clear title to the dweliing, whereas
E. Condominium apartment owners have a title to their dwelling that is free and clear, while | 
