I would say "Are the tomatoes ripe yet?"
Why I say this?
I say this because One, It has correct punctuation. Two, Subject and Predicate.
How did I pick this one?
In the 2nd one it doesnt have a proper Starting word For example: Who, Are, What, Why, ect. In the 3rd one It doesn't have the Question mark at the end. So it cant be it. And the last one, I dont think you would start a Sentance with "Behind"
Hope it helped! ^ ^
