You do not know what you are talking about. You are grasping at straws. If you are "focusing", why wouldn't you just say "This cat is extraordinary." Clearly the people that have assembled this course do not confer with native English speakers before that grind out these ridiculous sentences that are clumsy, have no meter, and no common use.
Both English sentences say the exact same thing, and have the same meaning. If you think otherwise, go ask other English speakers. Don't pretend to know what you are talking about by making up a story.
The intent of my question was purely rhetorical. The two sentences in English that you offered have no difference except one has an article, and the other has the article omitted. There is no difference in the meaning. The exercise in the app asked for an English translation. I maintain that either answer is correct.
I did not expect you to actually respond, because there is no difference in meaning of the two English sentences. But instead, you have the audacity to lie and try to sound like you know what you are talking about.
You seem to be the unofficial "hall monitor" here, but I would call you a "troll". You have no official capacity here and no known qualifications to your credit, only that you patrol this area making incorrect statements and pretending to know what you are talking about. Perhaps you should spend more time studying your made-up imaginary languages, like Klingon and Valerian.
Oh, and by the way, the words "a" and "an" are articles.