Hmmm! I wrote he argues with her, since that is one of the translations for dibatte in the dropdown menu...but it marked me as incorrect???
In my dictionary (Garzanti/Hazon) the only translations are "to debate/do discuss"
Well, the dictionaries state that dibatte means debates, but when you hover over the word in duolingo it states that dibatte means also argues. So the duolingo dictionary should be corrected.