British shipping losses, especially since the declaration of unrestricted submarine warfare, had risen dangerously....But the entry of the United States into the war made the German submarine warfare an evident failure, because thereafter the number of ships convoyed and the number of ships protecting the convoys was increased steadily. Convoys of ships transporting food, war materials, and troops arrived safely in Britain, and the rate of shipping construction soon exceeded the rate of loss."
How did the United Stats navy help break Germany's submarie blockade of Britain?
A. by completely destroying the German submarine fleet
B. by finding new routes around the German submarine fleet
C. by strengthening the convoys
D by sending supplies to France rather than Britain.