Sentence Correction

5. Although it is conceivable that certain electronic
devices implanted in the brain may someday
correct blindness caused by nerve damage,
there is now no clear evidence of their ability to
do it.
(A) of their ability to do it
(B) of their doing that
(C) that they can do so
(D) that they might one day be able to do it
(E) to do so


OA is C. Quite simple. But, my question is the pronoun"it" in the starting of the sentence refer to what?
If it refers to "Electronic devices", then what "they can do so" refers it.
Is not it a ambigous pronoun reference.
What if the one of the ans is "that it can do so"

But, I have seen lot of question, it and they reference like this. What's the rule for it.
Please explain in detail.

it = certain electronic devices implanted in the brain may someday
correct blindness caused by nerve damage

hariharakarthi wrote:5. Although it is conceivable that certain electronic
devices implanted in the brain c,
there is now no clear evidence of their ability to
do it.
(A) of their ability to do it
(B) of their doing that
(C) that they can do so
(D) that they might one day be able to do it
(E) to do so


OA is C. Quite simple. But, my question is the pronoun"it" in the starting of the sentence refer to what?
If it refers to "Electronic devices", then what "they can do so" refers it.
Is not it a ambigous pronoun reference.
What if the one of the ans is "that it can do so"

But, I have seen lot of question, it and they reference like this. What's the rule for it.
Please explain in detail.

C is CORRECT.
IT can't be correct. Because, here we should refer "may someday
correct blindness caused by nerve damage". so, we should use SO rather than IT

IT in A doesn't refer to anything, that's why IT is incorrect.
We have to say "SO" in this case.