Mitochondria are a<span>n organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. It has a double membrane, the inner layer being folded inward to form layers (cristae).</span>
The writing materials,the envelopes and the stamps are all made of paper and this led to a great waste as the papers have to be disposed after use. This is not the case with electronic mails. Electronic mails do not need paper at all and it has drastically reduce the amount of papers that is used in writing letters.
I hope this helps :)
The answer to your question would be letter D
