ANS:C - Ozone filter

In some printers, to transfer the devoled image from the drum to the paper and then coronas (older laser printers that have \'corona wires\'. ) produces ozone. Ozone is not good for humans as it is an oxidizer and can damage lung tissue etc. So it must be filtered out. Ozone filters made from folded paper with a thin layer of activated carbon glued on prevent from ozone.