关于介词宾语被代词指代：manhattan的一个疑点

roostme

manhattan在讲所有格指代中举了以下例子：
Wrong：The board is investigating several executives’ compensation packages in order to determine how much may have been improperly awarded to THEM.

Right：The board is investigating compensation packages of several executives in order to determine how much THEY may have been improperly awarded.
在right的句子中they指代several executives，注意several executives是修饰packages的，several executives应该不可以被指代。

OG13第81题：
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选项中it的解释：A    Because sloth is the object of a preposition and not the subject of the sentence, there is no reasonable antecedent for the pronoun it; 因为sloth是介词宾语，而不是句子的主语，所以it没有合理指代对象。
问题：介词宾语是否不可以被代词指代？