The correct response is:
The polyethylene wrap probably caused the browning since it contains ethylene which would speed up the ripening process.
Ethylene is a natural plant hormone produced by fruits, including bananas, that promotes ripening. If the polyethylene wrap allows for ethylene to build up, it could hasten the ripening process and consequently lead to browning. In contrast, polyvinyl (as a plastic) tends to trap ethylene gases, which might not significantly accelerate the ripening process as much as polyethylene would. Thus, the use of polyethylene wrap could be more likely to cause browning due to its interaction with ethylene.