Which of the following would contain the fewest base pairs, if starting with the sane size eukaryotic gene?

The higher you go up the less oxygen there is 

Mitochondria produce atp, a high energy compound. atp is used for all sorts of enzyme-mediated reactions, such as making proteins/nucleotides/etc, certain compounds cross the cell membrane, muscles move, etc.  without this source of energy, a cell will die. it will not be able to repair itself, defend against pathogens, etc.

On edgenuity it is d: watermelons