The answer to the question about how fish breathe is letter B or because they have gills. All kinds of fish use a special organ – gills – so they can breathe the oxygen which is dissolved in water. The gills are found inside the mouth and throat of a fish – the mouth and throat force the water over the gills and is in turn dissolved into oxygen through the blood vessels. The dissolved oxygen will then move through the walls of the blood vessels and will then enter the blood.
Once the blood has been fully oxygenated, it will be pumped back toward its body to produce energy needed for the metabolic processes in their body. Please note, however, that some fish have two gills while other can have as many as five gills.