What Helped the Allies Gain the Advantage in the Battle

What helped the Allies gain the advantage in the Battle of the Atlantic?

A) The Allies decoded German messages that indicated where the U-boats were.
B) The Allies had a submarine advantage over the Germans.
C) The Allied aircraft carrier superiority countered the German U-boat advantage.
D) The Allies utilized aerial precision bombing of German targets.
E) The Allies bypassed the Atlantic to confront the Germans directly in Europe.