Here is a goal: How do you ripen bananas?

Which way makes more sense to accomplish this goal?

Available choices: (a). Place bananas in a brown paper bag and close loosely. Ethylene will build up and circulate within the bag, speeding up the ripening process. Check at certain intervals in order to take them out at your desired ripeness.. (b). Place bananas in a brown plastic bag and close loosely. Ethylene will build up and circulate within the bag, speeding up the ripening process. Check at certain intervals in order to take them out at your desired ripeness..
(a).