What Is the Likely Outcome If You Were Able to Force

What is the likely outcome if you were able to force water through fish gills in the opposite direction?

A) blood's oxygen concentration would not be able to exceed 50%
B) countercurrent exchange would be compromised and load of oxygen into the blood would cease
C) blood flow would reverse to compensate for reversed water flow
D) concurrent exchange will be compromised
E) no effect