You should aways have the answer "Non-exploitable code" for every question. For some questions, the lack of this answer makes it clear that there is a vulnerabi

You should aways have the answer "Non-exploitable code" for every question. For some questions, the lack of this answer makes it clear that there is a vulnerability, and the structure of the question makes it obvious which one of the answers is most likely (e.g., no SQL or methods dealing with SQL exclude all SQL based answers, a question with "sleep" is highly likely to be a DOS by Sleep, etc.) I'm not a CS guy, but I was able to deduce a lot of the answers just from how the question was structured. EDIT: The actual response in the app is "Non-exploitable code". Updated my comment to reflect this