Refer to the Figure Showing Models of Concurrent and Countercurrent

Refer to the figure showing models of concurrent and countercurrent gas exchange. If you did an experiment in which you measured the oxygen saturation of the blood and water going through a gill in goldfish, your results would look most like panel _______, because _______.

A) A; fish have an efficient concurrent flow pattern of blood and water through their gills
B) B; fish have an efficient concurrent flow pattern of blood and water through their gills
C) A; fish have a flow pattern through their gills that optimizes the PO₂ gradient between water and blood
D) B; fish have a flow pattern through their gills that optimizes the PO₂ gradient between water and blood
E) B; fish have a countercurrent flow pattern of blood and water through their gills