During the final years of world war ii, how did the allies gain control of the north atlantic?
they used u-boats to sink german ships.
they used fighters to provide air support for their ships.
they used better anti-submarine technology.
they used allied submarines to defeat german ones.

C. Better anti-submarine technology

The best answer is They used better anti-submarine technology.

By the end of 1942, the Allies had discovered ways to thwart the U-boats. A key breakthrough occurred when British experts deciphered the German naval radio codes, enabling Allied convoys to steer clear of U-boats or to hunt them down. New technology also helped: sonar and radar enabled Allied ships to track submarines. The most effective tactic was to organize the ships into convoys with protective warships surrounding them. After May 1943, the U-boats were on the defensive, and Allied shipping losses fell significantly. The U-boats kept up the Battle of the Atlantic until the war’s end; when Germany finally collapsed, almost 50 submarines were still at sea, but 783 had been destroyed.

this isn't a question and if you're going to list things be kind and use commas.