OG verbal 分册的语法 问题

求助一道OG verbal 分册的语法， 找不出考点， 想了久不明白；

The Anasazi settlements at Chaco Canyon were built on a spectacularscale, with more than 75 carefully engineered structures, of up to 600 roomseach, were connected by a complex regional system of roads.

(A)  scale,with more than 75 carefully engineered structures, of up to 600 rooms each,were

(B)  scale,with more than 75 carefully engineered structures, of up to 600 rooms each,

(C)  scaleof more than 75 carefully engineered structures, of up to 600 rooms each, eachthat had been

(D)  scaleof more than 75 carefully engineered structures, of up to 600 rooms each andwith each

(E)  scaleof more than 75 carefully engineered structures of up to 600 rooms, each had been

答案是 B

我选的是A， 解释说structures 是with 的宾语， 如果用were connected 这样没有主语。。。。。 想不明白。。。