Mostly the reasons were economic. The country's economy was dismembered when it entered the great depression and they had to take care of that. The South used this to reinforce its values because nobody was bothering them since the great depression forced the government to move its focus on something else.
Answer: D is right. But there are also many other reasons.
Explanation: League of Nations was formed by Allied powers (from the WW I) so consequently it was viewed as "League of Victors". Moreover USA did not join, may other states did not join and later on League of Nations was unable the prevent outbreak of WW II.
Ganges? Let me know if this is it?
Oligarchy, government by the few, especially despotic power exercised by a small and privileged group for corrupt or selfish purposes. Aristotle used the term oligarchia to designate the rule of the few when it was exercised not by the best but by bad men unjustly.