You Have a Bowl Full of Slightly Under-Ripe Bananas That

You have a bowl full of slightly under-ripe bananas that you decide to leave for a few days until they are ready to eat. After returning a few days later to eat a banana, you discover they are now black and over-ripe. Upon further investigation you also discover a very over-ripe banana at the bottom of the bowl that you had not previously noticed. How would you explain this observation?

A) The over-ripe banana released methylene which triggered rapid ripening in the other bananas.
B) The over-ripe banana released ethanol which triggered rapid ripening in the other bananas.
C) The over-ripe banana released cytokinins which triggered rapid ripening in the other bananas.
D) The over-ripe banana released auxins which triggered rapid ripening in the other bananas.
E) The over-ripe banana released ethylene which triggered rapid ripening in the other bananas.