This riddle will be easy for a Whovian (Doctor Who fan) if they read the option for normal people. Normal people will find this difficult if they read the option for Whovians. To each their own, so please only read the option written for you.
No matter which option you Whovians choose, if you're a die-hard fan, it'll be pretty easy. Normal people will have to work slightly harder, but it still should be quite easy.
Good luck, and have fun!
~ Kestrel Knight