B wouldn't work, you have to much postive pressure (too much intake, not enough exhaust). You want to look up your fans for their CFM, then get them somewhat close for intake vs. exhaust. If you are more intake than exhaust, you are 'positive pressure' and the flip side is 'negative pressure'. There are arguements for both, but you can't have the intake vs. exhaust so far out of whack. Don't forget to include your PSU fan as an exhaust when you start running numbers.