hi,
lets see what is the Independent clause here--
Danica Patrick is a notable racer on the Indy circuit,
It is a fact, or a reality

In C we use a noun modifier
whereas in D we use VERB+ing modifier, and a verb+ing modifier generally talks of the result of the preceding clause

Here C is therefore more appropriate as we are talking of a FACT..
May be usage of THAT instead of WHICH would have been slightly better due to MOST of Qs using which with COMMAS, But it is correct the way it is..
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Danica Patrick is a notable racer on the Indy circuit, which once again shows that women can compete with men. - Incorrect
(A)which once again shows that women can compete with men - which modifies the circuit and does not make sense - Incorrect
(B)which once again shows that women are able to complete with men - which modifies the circuit and does not make sense
(C)a fact which once again shows that women can compete with men - Correct option. In the first part of the sentence we have a fact that someone is a notable racer, in the second part we describe what this fact is.
(D)showing once again that women can compete with men - In the first half of the sentence we stated the fact who is Danica Patrick, there was no any action to use showing. If we change the first part to something like: Danica Patrick performed excellently as a racer on the Indy circuit this year then we could use option (d) as an answer. - Incorrect
(E)proof once again that women can compete with men - there was no debate to show the proof, there was just statement of the fact - Incorrect

(A)which once again shows that women can compete with men

==>> Which is wrong here, it nonsensically modifying Indy Circuit
INCORRECT

(B)which once again shows that women are able to complete with men

==>> Which is wrong here, it nonsensically modifying Indy Circuit

INCORRECT

(C)a fact which once again shows that women can compete with men

INCORRECT

A Fact which --> is wordy and awkward. No need of 'A fact"

(D)showing once again that women can compete with men
CORRECT, Best among all

Showing (Verb-ing) modifier is modfying the previous clause. Clear and Concise

(E)proof once again that women can compete with men

INCORRECT

Proof (doesn't sound good). We need to have a modifier here. 'Proving' should the better

IMO D

Danica Patrick is a notable racer on the Indy circuit, which once again shows that women can compete with men.
(A)which once again shows that women can compete with men
In this option WHICH does not refers to Circuit but the whole action "Danica Patrick is a notable racer on the Indy circuit". As per GMAT, WHICH can not refer to a action. Thus Incorrect

(B)which once again shows that women are able to complete with men
In this option WHICH does not refers to Circuit but the whole action "Danica Patrick is a notable racer on the Indy circuit". As per GMAT, WHICH can not refer to a action. Moreover, there is no need to use ABLE TO. Thus Incorrect

(C)a fact which once again shows that women can compete with men
"Danica Patrick is a notable racer on the Indy circuit" is not a FACT but just an INSTANCE (One Case). More use of WHICH is incorrect here as per GMAT. Instead, THAT should be used. Thus Incorrect

(D)showing once again that women can compete with men
Present participle SHOWING correctly modifies the previous clause. Correct

(E)proof once again that women can compete with men
"Danica Patrick is a notable racer on the Indy circuit" is not a PROOF but just an INSTANCE (One Case). Thus Incorrect

OE edited .

Here's the OA -

Vague use of pronoun. “Which” refers to the noun it follows, but in this sentence it is illogical, as not the Indy circuit shows that women can compete with men, but the whole situation. Therefore, A and B can be eliminated. In Choice (C), “which” clearly refers to “fact.” Choice (D) is too general and ambiguous. Choice (E) changes the original meaning by adding word “proof”.

The correct answer is C

Danica Patrick is a notable racer on the Indy circuit, -ing modifier blah blah blah

When we need a ing modifier.
1) if ing modifier explains how subject is performing that particular action.
2) if action done by the subject results into some outcome or result.

Here in option D.
D. Showing that women can also compete with men.

First half of the sentence is not stating any action performed; first half of the sentence is presenting a fact not any action is done by the subject.
Thus, usage of ing modifier is not correct here.

this is agreat question to learn a lot from.
chetan2u what do you think about this showing once again that and once again shows that?
Your explanation pointed to that but it wasnt very clear. Can u please explain the difference in placing of "showing once again"?

Disagreement is a word that suits this question

and it creates such things quite a lot

Firstly let me get to the meaning : a particular gender does something noticeable, which shows that one particular gender can compete with other

I feel a clear situation is there for a cause and effect, hence D seems right

C is wordy with use of word *a fact* basically it's not used as fact in very literal meaning
use of a fact which once again shows that women can compete with men

here the use of relative modifier is somewhat problematic, which is used to describe non-essential info and precedes by comma (use of that in place of which can make it better)
Again it's too much stretched to use two times relative modifier in this case, D filters out this thing in better way.

Hi,
Nez, I feel 'once again' actually just tells us that there are other things that have shown the VIEW spoken about..
So, the sentence should not be wrong with or without it.. Thats my view because I have not come across any Q where such thing is not allowed..

eg,
roger federer won the wimbelbon this year, showing once again that he is the best in the game..
Here 'showing' modifier is better, as he is best in the game is " an outcome of the preceding clause"
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Don't you think in C " a fact which once again shows that women can compete with Men " conveys that this fact has already shown the same and is showing again? :S
D on the other hand makes sense to me .
Her being a notable driver presents the effect that women can compete with men!

sayantanc2k , chetan2u

X once again shows that ......
The above implies that the showing is happening again - previously X might have shown or someone / something else might have shown.

The reasoning is applicable for D as well.

The only problem I see in C is that no comma is used before the non-essential modifier "which" (though in GMAT an option would not be wrong just because of punctuation error).

I see no problem with D.

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