The correct answer is C) The head of the tow will tend to sheer away from the revetment. When pushing barges ahead close to a steep revetment where there is no current, the head of the tow will tend to sheer away from the revetment. This is due to the Venturi effect, where the flow of water is constricted between the barges and the revetment, causing an increase in water velocity and a decrease in pressure along the revetment. This pressure differential pushes the head of the tow away from the revetment. The other answer choices are incorrect because: A) The speed over the ground will not increase, as the Venturi effect only affects the water flow, not the overall speed of the tow. B) The stern of the towboat will not tend to sheer away, as the Venturi effect is acting on the head of the tow, not the stern.