Option A :- Incorrect
This has a wrongly placed modifier. It is assumed that the clause that is to be treated has to begin with the subject of the sentence.

Option B :- Incorrect
This option suffers same fate as option A above, the modifier is being misplaced and the subject of the sentence which is Babara McClintock has to kick start the long phrase.

Option C :- Incorrect
that led will be chosen over it led. This is a sequential statement from the preceding one so what Babara McClintock did 'that led'is a better choice that should follow.

Option D :- correct
This option is very straightforward and it has brevity. It contains no grammatical errors, modifiers well placed and the subject was already at at the right place.

Option E :- Incorrect
This option is quite similar to to option D above and looks to be the best choice too. But the use of the relative pronoun 'who' which makes the slightly shows tautology and inconciseness makes the option looks terrible.