Correct option is (B) gills
In fishes, respiration takes place by gills. Fish take in oxygen-rich water via their mouths and pump it over their gills. When water moves over the gills, the blood within the capillary network of gills takes up the dissolved oxygen. Then, the circulatory system supplies oxygen to all tissues of the body and finally to the cells. Carbon dioxide is taken from the cells to the blood, circulated back to the gills, and is then eliminated through the gills from the body.
