All,
I completely disagree that option B is correct. I believe that B is rather irrelevant for it doesn't discuss the change in the ability to hear, but just the difference in men's and women's ability (which is not the topic of the argument). The topic of the argument involve the change of hearing ability.
The Statement: As they get older, women usually maintain their ability to hear higher frequencies longer than men do. This is only because men are usually exposed to more dangerously loud noises at work and during recreation.
The statement above clearly states that men do not maintain their ability only because they are exposed to loud noises. More so than women do. Option B: The difference between men and women in their ability to hear higher frequencies is entirely unrelated to any difference in the structure of the inner ear.
This statement does not talk about the what happens to men's ability as they grow older but, just the difference in their ability itself. Now initially when they were not old, men's ability to hear higher frequency could be different to that of women's because of several reasons (unmentioned in the original argument - the argument only talks about the change in the ability) such as the structure of inner ear. The difference in men and women's ability to hear noises is not the topic here. Instead the topic is the change in the ability. Hence option B cannot be correct. Think of it this way - "Initially (when they were not old) the difference in their ability to hear high frequency noises was due to the different structures of the inner ear. "
Is this statement in any way negated by the argument in any way? No, the argument discusses deterioration in men's ability. It does not say anything about the difference in their abilities to hear higher frequencies.
Its the same as saying men lose more hair only because of work pressure. But men can have less hair because of genetics to begin with. So the amount of hair on men's head does not only depend on the work pressure. I t depends on genetics as well. The loss (change) depends only on work pressure and not the genetics. (this is not factual, just a statement)
Which would mean the negation of B can be true and so it cannot be the answer.