I found an error in the app and took a screen shot of it. No way to tell Duolingo though! I've tried searching for a contact button but there isn't one. Last I checked, "Mis padres estan muertos," means, "My parents are dead." However, the word "parents" was not in the word bank. The only word I could possibly use was GATOS or cats. Padres does not mean cats, yet I had to select it as there was no other option. Funny part is, afterwards, the app popped up and said "Correct answer!" Ummm, no, I don't think so. And yet, there is NO way to contact duolingo so they know there is an error they should fix. Oh well. Not my loss, but, it may confuse me later when I don't know if the answer is right. I wish I could tell someone.
I think once you answer a question, where it says correct or incorrect there is a button saying report an error.
That's pretty funny. From the discussion, it appears that this error has been introduced in the past few days. You are not the only one to notice. https://www.duolingo.com/comment/332173
The best thing to do is generally to use the report button from the website the next time it comes up. I haven't seen the report button in the app on iOS although I've not used the app much and so might have missed it.
Other than that, the only things that come to mind are to contact one or moderators for that course and/or report it in troubleshooting.