Two issues spotted here. Let's analyse each case

(1) Woman Judge: Here, woman is a "Noun Adjective" extended as "Judges of Women", which distorts the meaning. The author wants to say that judges, who are women. Putting simply - 'Women Judges' can have two meanings. So, we can eliminate option B and D.

(2) Sub - Verb agreement: The Subject here is Proportion, and this is place in the best way to pick the wrong one within the "prepositional phrase", need to skip them

Option A - Incorrect
The important word here is proportion, and it should refers to a singular verb. Therefore, the usage of "have" is wrong.
-"to a comparable extent" is wordy", "comparably" could have been preferred in usage here.

Option B - Incorrect
*The usage of "have" is incorrect.
*"Proportion" in this case only compares with women judges and partners at major law firms. Note, the missing reference of women for partners, which impies that the proportion is of all women judges and all partners (male or females) at major law firm.

Option C - Correct
Proportion is clearly between "judges and partners at major law firms who are women". Hence, the usage of "comparably" is correct.

Option D - Incorrect
The word 'despite' incorporated here brings in contrast to this sentence. In addition, the usage of "yet" is redundant as it makes the sentence awkward.

Option E - Incorrect
Same reason as applied to option D on the usage of 'contrast' and 'yet.