The correct answer is A) to defend the signing of the nonaggression pact with Hitler.
The purpose of Stalin's speech is to defend the signing of the nonaggression pact with Hitler.
Joseph Stalin and Adolph Hitler signed a nonaggression pact on August 23, 1939. In the so-called German-Soviet Nonaggression Pact, both countries agreed of not taking any military aggression or action against each other for a period of 10 years. The pact only lasted two years because, in 1941, Hitler invaded the Soviet Union. So, yes, the purpose of Stalin's speech is to defend the signing of the nonaggression pact with Hitler.