whichNon-defining relative: "The Amazon rainforest, _____ is home to millions of species, faces unprecedented threats."The Amazon rainforest, which is home to millions of species, faces unprecedented threats.NoteThe Amazon rainforest, which is home to millions of species, faces unprecedented threats.Elon.io is an online learning platformWe have an entire course teaching IELTS Vocabulary — Band 7+ grammar and vocabulary.Start learning IELTS Vocabulary — Band 7+ now