"Apples are red or green."
Translation:Les pommes sont rouges ou vertes.
In the absence of any article in English:
• Try adding “in general” to the end of your sentence, and if it works, use the definite article (le, la, l', les).
• Try adding "some" in front of the singular object, and if it works, use the partitive article (du, de la, de l')
• Try adding "more than one" in front of the plural object, and if it works, use the plural indefinite article (des).
I think I understood your meaning - but I think you were mistaken in your reading the options presented. 'Les pommes sont rouges ou vertes.' looks very similar to 'Le pommes sont rouges ou vertes', especially if you're on mobile with smaller font sizes. I was saying I nearly made the same mistake of selecting both when answering this question... Though of course it could have been a bug with the 'Les' option being presented twice.
But nevertheless the discussion is useful for the moderators to ensure bugs are ironed out.