OG 78 代词的那个问题

jaze

OG 78
Fossils of the arm of a sloth found in Puerto Rico in 1991. and dated at 34 million years old, made it the earliest known mammal of the Greater Antilles Islands.
(A)    sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of
(B)    sloth, that they found in Puerto Rico in 1991, has been dated at 34 million years old, thus making it the earliest mammal known on
(C)     sloth that was found in Puerto Rico in 1991, was dated at 34 million years old, making this the earliest known mammal of
(D)    sloth, found in Puerto Rico in 1991, have been dated at 34 million years old, making the sloth the earliest known mammal on
(E)    sloth which, found in Puerto Rico in 1991, was dated at 34 million years old, made the sloth the earliest known mammal of

OG对A的解释中有一条是

Because sloth is the object of a preposition and not the subject of the sentence, there is no reasonable antecedent for the pronoun it;
不太明白这个是什么意思， 在前面做介词的宾语， 就不能被指代了？ 不是只要是名词就可以被指代吗？ 这个是什么规则啊？

flywer

我觉得可能是还是为了解释有歧义的存在吧
fossils of the arm of a sloth...因为sloth前面还有arm,所以无法明确it指代的是sloth还是arm
OG关于object跟subject的解释应该就是指这一点，因为of的前面还有一个of,所以不能准确的指代    如果是fossils of a sloth我想A就应该没问题了
这个解释主要应该是为了说明there is no reasonable antecedent for the pronoun it吧

mlvince

这里的it可以指代arm和 sloth。而且fossiles make it the earliest known mammal 不对，应该是前面一段话使the earliest known mammal ，所以应该用making