prep破解版题目，请教大家

Sophin

Archaeologists in Egypt

have excavated a 5,000-year-old wooden hull that is the earliest surviving example of a "built" boat--in other words, a boat constructed out of planks fitted together--and that thus represents a major advance, in terms of boat-building technology, over the dugout logs and reed vessels of more ancient vintage.

(A) together--and that thus represents

(B) together--and this has represented

(C) together, and it represents

(D) together that was representing

(E) together to represent

答案是A，各位大牛们，我实在不知道怎么判断这个题目是A的。。。

毛毛carina

这里是用破折号来置入插入语 in other words, a boat constructed out of planks fitted together

主句是Archaeologists in Egypt  have excavated a 5,000-year-old wooden hull

后面用两个从句来解释说明hull

hull that …… and that ……
句型很完美~~~~~