Here is my take on this one
the conclusion is "Therefore, the reason there are so few women who win elections for these offices is not that women have difficulty winning elections but that so few women want to run."
now we need to target why "so few women want to run" - we need to find an answer to say that women actually want to run but because of some reason they are unable to do so. so with this thinking lets look at our options
(A) Last year the proportion of women incumbents who won reelection was smaller than the proportion of men incumbents who won reelection.
(this doesn't weaken the conclusion)
(B) Few women who run for state and national offices run against other women.
(The conclusion is about "Few women want to run(voluntarily)")
(C) Most women who have no strong desire to be politicians never run for state and national offices.
(This strengthens the conclusion (I think))
(D) The proportion of people holding local offices who are women is smaller than the proportion of people holding state and national offices who are women.
(not relevant)
(E) Many more women than men who want to run for state and national offices do not because they cannot get adequate funding for their campaigns.
(so this successfully states a secondary reason why so few women run for offices(its not a voluntary decision, the decision is based on other things(in this case funds))
- Let me know if someone feels this is wrong.