Operation Overlord was the code name for the Allied invasion of Normandy. The correct option in regards to the given question is option "a".
The German forces surrendered en masse to U.S. and British forces rather than to the Soviets towards the end of the war because the Germans knew that the Americans and the British would treat them as per the Geneva Convention, while the Russians would not care because the Germans had previously treated the Russians in a merciless manner. This made the Germans not surrender to the Russians although the Germans knew that there might be some cases of atrocities in the hands of the British and Americans as well.
