语法求助

消逝是我的命运

For protection from the summer sun, the Mojave lived in open-sided, flat-topped dwellings known as shades, each a roof of poles and arrowweed supported by posts set in a rectangle.



A.each a roof of poles and arrowweed

B.each a roof of poles and arrowweed that are being

C.with each being a roof of poles and arrowweed

D.with roofs of poles and arrowweed to be

E.with roofs of poles and arrowweed that are  这题为嘛选a。。。