Question: Fish breathe by passing water across their gill filaments. This is a remarkably efficient process because they use counter current exchange. Counter current exchange solves which of the following problems? Need Assignment Help? Question options: A) If water and blood flowed in the same direction oxygen concentration would never reach equilibrium B) Water and blood do not flow in the same direction so they are always at 50% saturation C) If water and blood flowed in the same direction oxygen concentration would reach equilibrium at 50% saturation D) Water and blood do not exchange oxygen