"Who pushes the button?"
This is the second time I've hastily mistaken タバコ for ボタン。just because I'm a lazy reader, mostly. But it's pretty tricky, if not rude, of Duo to put two new, same sized katakana words always together in every translation that uses cards. (I don't really blame you, you big lovable bird. Just poking some fun at you)
To add to this, I'm pretty sure the underlying rule here is that interrogatives can't be topicalised in Japanese (which kind of makes sence, since the topic is just what the people involved in the conversation are talking about, and I really can't think of what it would mean to be talking about "who" or any other interrogative).