98% sure that it's number four.
Answer:
C. Earthquake
Explanation:
Han dynasty was known as one of the most devastating period in Chinese agricultural history. The country experiences series of natural disasters that destroyed a lot of Their agricultural lands.
It started from deforestation ordered by the empire in order to make various equipment's and infrastructure for the military's.
Trees have the ability prevent sediment runoff which can hold a huge amount of water. During the period of heavy rain, the amount of water that can usually sustained by the forest were let loose and came down to the citizens' resident. Destroying a lof of their farms in the process.
After that, the han dynasty had to deal with the exact opposite situation, when the country undergone some period of drought when very little rainfall happen. This also caused a lot of crop failures due to inability to fulfill the crops' water needs.
At their beginning, the Arabs were an incredibly weak and loose collection of cities that could have easily been destroyed by Rome, yet the long peace with Rome led to prosperity, therefore B is the answer.
D. The study of a society and its natural environment, would be the closest definition
