"This is crazy."
Translation:C'est fou !
Interestingly, it did not give "fou" as an option when I cheated. I used "dingue" and got marked wrong. Of course, that's what I get for cheating, but it was still weird to have it offer three incorrect options.
No, "c'est bête" means (roughly) "that's a pity". But you can use: "c'est dingue !" (amazing)