Answer:
a Theory
Explanation:
A theory is an initial explanation to an event/occurrence which is made based on an educated guess that can be considered as 'scientifically plausible' . (This means that we can't really hold a theory as fact since it hasn't been scientifically proven. )
The excerpt above fill all requirements of a theory:
1. It tried to explain a certain occurrence (how countries become wealthier their cultures shift to become more tolerant and open )
2. It is an educated guess (It is mentioned that Professor Chang has spent years studying human history and social change , this means that he had at least some level of expertise regarding the subject)
3. But it has not been really proven yet, since Professor Chang hasn't develop a scientific research to test the theory.
