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

选C

AB和D的owner与后面不对称

E dwelling that is free 是 n. that is 结构

所以选C

whereas 是表示转折关系的连词 正确

thanks for your explaination