Sentence Correction

Given its authoritative coverage of other science topics, the textbook's chapter on genetics is surprisingly tentative, which leads one to doubt the author's scholarship in that particular area.
Question

1)the textbook's chapter on genetics is surprisingly tentative, which leads

2)the chapter of the textbook on genetics is surprisingly tentative, leading

3)the textbook contains a surprising and tentative chapter on genetics,which leads

4)the textbook's chapter on genetics is surprisingly tentative and leads

5)the textbook is surprisingly tentative in its chapter on genetics, leading

OA5

We can select the OA because of COMMA + VERBing concept or any other reason is needed to select the OA.

If COMMA + VERBing is the reason for OA , then please experts I really need your help on this.

Please explain.

Thanks

Usage of which refers to nearest noun. So the options using which refer to Genetics. Genetics is not leading to the doubt. eliminate 1,3

Usage of AND leads is incorrect since this usage can denote two separate actions.

There is close competition between 2 and 5. the only difference is in meaning. the Chapter is most probably not leading to the doubt. The Book is leading to the doubt.
there is a clue in the begining of the sentence. Given its authoritative coverage of other science topics, - So the text book has other topics as well. So it should be the textbook.

Hi ,

Thanks for your reply, but I really need a help on COMMA + VERBing concept.

@Experts, please help me on this.

Thanks