GWD

lena110220

GWD-10-Q3

For protection from the summer sun, the Mojave lived in open-sided, flat-topped dwellings known as shades, each a roof of poles and arrow
            weed 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

我选D

dphxmg

"each"(,which, as pronoun, here means "each shade") is in apposition to "a roof...set in a rectangle". So we can exclude c,d,and e.
In this context, the writer intends to explain the state rather than the action. So b can be excluded.