紧急求助，题号和解释对不上

我已经作了8套了，可是正确率还是没有上来，现在很着急。我确实是总结得太少了，一般就看看答案就做下一套。现在看来不行了，必须要总结。我做的是31套版本的，看我找cd上的答案，怎么没有能对得上的？我第八套第一道verbal 题是

Q1:

The four-million-year-old fossilized skeleton known as Lucy is so small compared with many other skeletons presumed to be of the same species, and so some paleontologists have argued that Lucy represents a different lineage.

1. presumed to be of the same species, and so
2. presumed to be of the same species that
3. presumed that they are of the same species, and so
4. that they have presumed to be of the same species, so that
5. that they have presumed are of the same species, and