"why are you single"

The most dreaded question that I get asked almost daily, with an even more dreaded answer. I feel that this comment is almost a backhanded compliment. Sure, it's usually by someone who is surprised I'm single, but it also insinuates that there is something so wrong with being single. As if it is a state that you shouldn't be, without a reason. Do I ever ask people "why are you in a relationship?". One of these days I will give an answer other than "not sure!" and it will be one or all of the following:

a) Because I live in Toronto. Have you seen the girl to guy ratio?
b) Because of a) there is a significant lacking of cute, smart, single boys.
c) Because many guys fall for me. And Many/All of said guys have girlfriends and I don't believe in fairytales. Or wrecking homes.
d) Because I don't see the state of being single something that I have to get out of by "settling".
e) Because I am secretly a monster that eats the heads of all boys who I kiss.

Isn't it obvious? I'm single because I haven't found anyone that I can see myself with. That's it. That's all.

What is the answer to this ridiculous question?