请问一道gwd的题目

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.

1. sloth
        found in Puerto Rico in 1991, and dated at 34
        million years old, made it the earliest known mammal of
2. 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
3. sloth
        that was found in Puerto Rico in 1991, was dated at
        34 million years old, making this the earliest known mammal of
4. sloth,
        found in Puerto Rico in 1991, have been dated at 34
        million years old, making the sloth the earliest known mammal on
5. sloth
        which, found in Puerto Rico in 1991, was dated at
        34 million years old, made the sloth the earliest known mammal of

应该是D吧？

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. 

       it 指代错误, made的主语业错

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

时态错误, they 指代错误 it 指代错误,known on错误

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

勉勉强强对, making the sloth ~~~正确标志

 只是不明白为何要用现在完成时, 而且介词用on 好像业不妥当

E. sloth
     which, found in Puerto Rico in 1991, was dated at
     34 million years old, made the sloth the earliest known mammal of

was dated 错误
后面倒是对的