Zion, the fact that people have not voted in huge numbers, indicates that this is no way to conduct statistical analysis. The respondents are a self selecting sample who have an interest in the concept of UFOs as alien artifacts. I voted other, because it is the only one that fits: I don't believe UFO's are alien craft, so I can't say a). I don't reject the possibility outright, so I can't say b). I don't consider them unlikely on the basis that I have not presonally had an encounter with them (that would be crap science), but on the basis that nobody has had a convincing documented encounter., so I can't go for c). There are a zillion interesting other things to do, but UFOs are still intriguing, so I can't say d). That only leaves 'Other'.