I am not sure what the best approach is for these types of questions in dual passages.
I am unsure with the second part of choice "D" on how we know B uses it as a contrast for acquiring insider infomation.
From my understanding, the quoted lines in B are meant to show that if you are successful in the market then it was only by skills +info. And in a transparent market, everyone has the same info. But I am not quite seeing how the answer choice links it as a contrast to insider infomation.
I was also unsure about Choice "B".
In Choice B I think the description for A is fair because the following paragraph then said 'look, this is good, it allows stock prices to better reflect the true value of the stock with all the possible infomation'. For the description for Passage B under Choice B, I did not like the words when I chose it but I thought the conditional sentence in lines 40-42 was trying to get across some necessary condition.