Answer:
C. Abyssinia crisis
D. Manchuria
These issues are considered major failures of the League and contributed to the outbreak of WWI
Step-by-step explanation:
Both the Manchuria and Abyssinia crises sabotaged the belief people had in the League of Nation. They finally began to see the real power or authority over its members. The problem started when the Japanese claimed that the Chinese soldiers were behind the failed Manchurian railway in Korea.
The Manchurian railway was under the maintenance and was the responsibility of the Japan. On the other hand, during January-March 1932, Japan attacked Shanghai in turn China appealed to the League of Nations.
Another reason that made people doubt the credibility of the League of Nation is the Abyssinia crisis. In 1934, there was border dispute which led to a flare up between Abyssinia and the Italian Somaliland. The problem was further instigated when the Abyssinian emperor asked the League to arbitrate but the league simply banned the arms sales.
In the October 1935, the league came up with the plan that Italy should have some land in Abyssinia, but Italy attacked the Red Cross hospital with poison gas in Abyssinia.
While all this was going on, France and Britain refused to intervene. But the nail in the coffin was the secret pact Hoare-Laval Pact between the foreign secretary of Britain and the France Prime Minister which promised to give Abyssinia to Italy, while League of Nation was just a bystander.