When an unripe banana is sealed in a polythene bag,it remains green for many days. But if an apple is also sealed in the same bag,the banana ripens and turns yellow within a few days. The reason is that apple

• A
  Removes $O_2$ released by the banana and thus promotes ripening
• B
  Produces $CO_2$ which promotes ripening
• C
  Removes $CO_2$ which inhibits ripening
• D
  Releases ethylene which promotes ripening