I'm not sure this is write. Other sources have emphasized that when speaking of one's occupation, an article is not used. It should be "Sono contadino". I think other exercises here follow that practice.
This is getting very frustrating. I wrote the above and was marked incorrect. Said it was un'agricoltrice. Here it says contadino. Exactly what I wrote. Will report but this is the second time Duo has done this and that doesn't seem enough.
I think it's because "faccio il contadino" actually means "I do (the job of) the farmer." In this wording, "the farmer" is a generalization of all farmers. It's really just how i remember it. Can any NS italian clarify if you can use "un" as well?