"She wrote a short story."
Translation:Она написала рассказ.
"она написала короткий рассказ"? Or does рассказ already imply that the story is short?
Рассказ generally refers to short stories when talking about literature. It can be used during informal conversation as a story (I want to tell you a story, for example).
It's the different between perfective and imperfective, Russian verbs come in perfective/imperfective pairs. You might want to look up some grammar explanations on it, it's a bit difficult.
I'm with you. Рассказ translates as "story" in other exercises. Adding короткий shouldn't make the answer wrong.
Жаль, но буквально: "короткую историю" не приняло, хотя технически это тоже правильно.