No, it isnt a valid one I'm afraid. I use to teach HPL for many years and can be fairly certain that it would be a waste of time to contest, as there is no real risk of fainting after your cup of tea etc. Even if it is possible to argue that you might, the much bigger risk is to your ability to carry oxygen around your system and in all these exams only the most correct answer is right. Hope you got enough others correct that this one wont affect a good result overall.