The correct answer is B) It gives a spring effect to cushion the shock. When towing, a chain bridle is used on a wire hawser to create a spring effect that cushions the shock of the tow. The chain bridle acts as a shock absorber, absorbing the sudden forces and stresses that can occur during towing operations. This helps protect the towing vessel, the towed vessel, and the towing equipment from potential damage. The other answer choices are incorrect because: A) while an easy connection is important, it is not the main reason for using a chain bridle; C) the chain bridle does not necessarily prevent chafing compared to other methods; and D) the chain bridle does not eliminate the need for a swivel, which is still required to prevent twisting of the tow line.