It would be B or C. I'm SURE it would be C though.
"A" means to cause air to enter and circulate freely in (a room, building, etc.), which fire NEEDS air in order to be alive, so that would be BAD. "D" is saying to store guns in locked cabinets... which doesn't really make sense.
Explanation:
There are no sleeping positions that will increase your height faster. All you need is to have deep sleep as long as possible, usually 8–9 hrs.