You Prop Open the Gill Covers of a Fish,tie a String

Multiple Choice

You prop open the gill covers of a fish,tie a string around its tail,and tow it backward through the water.This action forces water to flow in the back of the gill covers,from back to front over the gills,and out through the fish's mouth.What effect would this backward movement have on gas exchange?

A) It would reduce efficiency of gas exchange.
B) It would change from CO₂ out and O₂ in to CO₂ in and O₂ out.
C) There would be no change in the efficiency of gas exchange.