Terjemahan:Bagian ini merah.
I've made this comment 1 month ago, just starting to learn Indonesian. Now I understand better why "ini", but Duolingo gave us habit to translate with "itu" and "-nya", and use "ini" for "this".
Oh I see. And I believe you've made a lot of progress in one month, tetap semangat!
Actually, "itu" is also correct