I really think that it doesn't really matter, as Duolingo is not an conversation guide, but a long term solution. So, with this question, the main purpose is to practice the vocabulary and the grammar using some easy sentences. So, the mnemonics will help you remember the words and the grammar will allow you to construct intelligent sentences instead of just learning them by hearth.
I read your comment and immediately thought "You spelled whale wrong, and of course it wouldn't make sense to just say 'Whale.'" But uh, oops.
I see your question now. And you should be able to just say "Quale?" as long as what you're referring to, like in English, has already been mentioned and it's clear what you're talking about (unless you really want to confuse people and just go around saying "Quale?" without any context).