Answer:
The 20th century is regarded as a century of crisis as a result of the unpleasant happenings all over the world during this period.
These happenings resulted in a mass loss of lives and properties as a result of most countries believing the best way to solve conflicts was through warfare . They include The World Wars , Russian Revolution, Economic depression , the different wars in Europe, Pacific and the holocaust.
If you consider the contribution of other anti-Aztec tribes and disease, then no. Cortez was merely the match that set fire to a very short fuse
Here you go :
http://www.institutions-africa.org/trackingdevelopment_archived/resources/docs/TD%20in%20SA%20and%20SSA_The%20primacy%20of%20policy.pdf
True.
Since scarcity is the basic economic problem, without scarcity there would be no need to study economics. Scarcity means when a particular commodity is not enough to satisfy human wants completely. So, if scarcity doesn't exist, it'll mean that everyone's wants will be fulfilled, hence the need to study economics will not be there.