There are a lot of sentences in Duolingo in which articles are used for both languages (when they should not). I wonder it happens because in Portuguese we use articles much more than in English (and these sentences were translated from Portuguese into English by Brazilians).
Below you can find at least 9 situations in which we should ommit the article in English whereas should use it in Portuguese:
Still weird, though. Humanity is a collection of individuals, yes? If so, how can unique apply as an adjective?