Translation:It is not short.
There no way tell who or what the subject is from the sentence.
All it says is "not short".
You can assert from the context. "Not short" is correct, but most likely you would be refering to something, as objects, as 短くis "short in lenght". So "It is not short" is a correct translation.
It is correct, but there's no way to tell what's being referred to without context. It's a faulty question.
The only meaning of the word offered is "short." New learners can't possibly know the connotation of 短い.
New learners are being introduced to the Japanese way of drawing inferences. The hypothetical conversation preceding the sentence would give context. The unmentioned subject would be understood. The new learner will soon discover that the "desu" at the end was not necessary either, because it follows an i-adjective. The whole sentence could have been "Not short," and the rest implied. We have to get the rhythm of this language the way it is, not the way we English speakers are used to.
I'm with Echo on this one. This is not the first time Duolingo falls short for me. I'm getting almost no grammar from this site. And dread of practicing (yes, dread) on Duolingo because I feel like a lot of times I'm tossing random answers at Duolingo and hopes something sticks. I'm just going by instincts a lot of times without actually understanding what I'm doing. And that feeling really, really sucks.
I interpreted it as "I am not short" is it a descriptor that wouldn't also be applied to people?
All those having confusion regarding whether みじかい refers to hieght of a person or object should visit this link and read the top 2 answers and their comments https://japanese.stackexchange.com/questions/594/when-would-you-use-%E4%BD%8E%E3%81%84-%E3%81%B2%E3%81%8F%E3%81%84-vs-%E7%9F%AD%E3%81%84-%E3%81%BF%E3%81%98%E3%81%8B%E3%81%84
TL;dr 低い【ひくい】means "low" It can used be used as in "low temperature", "low blood pressure" , etc and is used for describing a person's hieght (as "low in stature" or "head is low")
短い【みじかい】Means" short" as in short in length. If can be used like "short skirt" , "short hair" , "short scale" etc.
So here the sentence cannot mean "I am short" and is therefore "It is short"
Is "It is..." the only appropriate answer?
True, there is no "これ/それ/あれは..." in sight but, could the beginning of the sentence also be translated (interpreted) as "This/That is..."
Se ga takakunai/se no takakunai would be the equivalent if talking about a person's height.
Hey Duolingo, do you realize that you are not TEACHING anything? At all? Every lesson introduces something new, but as a student, I have to figure out what that is on my own. Gosh what a fake.