Political and economic helped both of their parties to gain support
The correct answer is Italy invades Ethiopia
The Fall of Nanjing happened in 1938 after a four months battle. Sudetenland was also annexed by Hitler in 1938. Invasion of Ethiopia happened during the Second Italo-Ethiopian war in 1935, which is 3 years before the other two events, even though the war with Ethiopia did last until 1939, which is four years after the invasion began.
If I am not mistaken D is your answer.
