Mobile app word quiz - "the" = цей, ция
I have a strong suspicion this is a limitation within the duolingo, nevertheless, as far as I know, this is technically wrong (see link for screenshots below)
Цей, ця , це = this. Because Ukrainian lacks definite articles and when they developed English course for Ukrainian speakers, I suspect "цей" was chosen to represent "the" better. For most Ukrainians articles in English is one of the more difficult concepts to master. I, myself, working for about 20 years with English still make mistakes quite often if I don't pay enough attention. Same team developed Ukrainian for English course and this feature was transferred to this course as well. So you're right, this is just a peculiarity that pertains to this specific Duolingo course.