Throw them away that is what you can do with them!
An apple becomes rotten when you bite it or cut it or just leave it in the sun, the apple starts to rot and then decompose.
You may throw up on spot, because of how gross that is, and you will be severely sick for a few days
because of oxygen
rotten apple will look smushy. well, you know. you will know if it is rotten if it doesn't look good... (-_-