Which of the following actions explains why Britain officially entered World War II?
the signing of the Pact of Steel between Hitler and Mussolini
the German invasion of the Soviet Union
the signing of German-Soviet Nonaggression Pact
the German invasion of Poland
the signing of the Pact of Steel between Hitler and Mussolini
the German invasion of the Soviet Union
the signing of German-Soviet Nonaggression Pact
the German invasion of Poland