Hearing that it was a female speaking, I wrote "Jem warzywa dlatego jestem silna," only to be told that I used the wrong word. I was corrected to "Jem warzywa dlatego jestem silny" If the speaker is a man with a high voice then that should be told to the student. If not, then explain when the genders female and male should be used as it relates to the person talking! Or is modern Polish slowly becoming gender neutral?
I think between what warfreak is saying which is these are computerized voices that are randomly male and female speaking these sentences and also the fact that Polish is very specific in the sounds of each vowel..it could not accept your translation of an “a” ending when the pronunciation we hear is an ending with “ y “ sound.
Also, I agree it is confusing to hear the opposite gendered voice say a sentence they normally wouldn’t in real life but if you go into it with the understanding that they’re testing you on listening for the actual pronunciation of the words and not worry about the gender of the voice then you’ll be successful for the most part.