kaplan sc

[GmatKiss]

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

[aspirant2011]

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

[gmatblood]

C

[1947]

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

C is correct as so correctly points to "correct blindness caused by nerve damage".
It can not point to this "correct blindness caused by nerve damage"