Prep破解SC中65题

Developed by Pennsylvania's Palatine Germans about 1750, they made Conestoga wagons with high wheels capable of crossing rutted roads, muddy flats, and the nonroads of the prairie and they had a floor curved upward on either end so as to prevent cargo from shifting on steep grades.
(A) they made Conestoga wagons with high wheels capable of crossing rutted roads, muddy flats, and the nonroads of the prairie and they had a floor curved upward on either end so as to prevent
(B) they made Conestoga wagons, which had high wheels capable of crossing rutted roads, muddy flats, and the nonroads of the prairie, and floors curved upward on their ends so that they prevented
(C) Conestoga wagons, with high wheels capable of crossing rutted roads, muddy flats, and the nonroads of the prairie, and had a floor that was curved upward at both ends to prevent
(D) Conestoga wagons had high wheels capable of crossing rutted roads, muddy flats, and the nonroads of the prairie, and a floor that was curved upward at both ends to prevent
(E) Conestoga wagons had high wheels capable of crossing rutted roads, muddy flats, and the nonroads of the prairie and floors curving upward at their ends so that it prevented

答案，D。

ABC肯定错。

E选项里面存在指代不清的问题。请教这个正确选项。

Conestoga wagons had high wheels capable of crossing rutted roads, muddy flats, and the nonroads of the prairie, and a floor that was curved upward at both ends to prevent

怎么会有两个and~~我当时徘徊了半天，以为前面的平行到and the nonroads of the prairie就结束了，然后后面,and是另外一句句子了，可是缺少成分，所以没敢选。

牛牛分析一下