Uff, now that's impressive. It's surpassed my critical limit for Greek letters and at this time of night I can't be sure I've understood it properly. It does though, look far more convincing that the "we-don't-know-what-to-do-about-atmosphere-so-let's-assume gravity-is-the-important-factor" school of thought and I have no reason to doubt that it's absolutely logical and correct.
BUT, and it's a big BUT, it depends on Temperature. Which, unless these candidates already know the temperatures of the atmospheres of the 3 planets, or have on a data sheet, means that this can't be what the examiners are thinking - even if it's 100% correct.
Sorry Worzo, first I thought you were over-simplifying, now I think it's too complicated. I just don't know where the happy medium is here.