It's fine. Just be aware that "ein Apfel" is nominative and "einen Apfel" is accusative.
Could you please explain what do you mean by Nominative and Accusative? I feel these might be important concepts of language for me to learn in order to advance further on in a better way. Thanks in advance!
So it's "Ein Apfel", right? It's not accusative in this case. The solution says it heard "Einen Apfel" and marked it correct...
It shouldn't though, because "One apple." is nominative. Or am I missing something?