Which common factor lead to the collapse of both the roman empire and the han dynasty a. as citizens turned more toward religious pursuits, their military forces suffered.
b. weak leaders used funds irresponsibly and could not gain the support of their subjects.
c. severe drought led to population decline and migration.
d. overfarming and urbanization depleted the natural resources of both regions.

assuming that you are talking about the one in egypt: hecka oil

explanation:

when a country suffers, for example, a drought period, the market product is affected for a low offer, in this case, potatoes; the government has to tax to the households, which have to give more money for the potatoes which they consume, that situation make them consume substitute goods even through loans, it could increase the financial market movement and the inflationary phenomena, the business has to increase salaries in order to the employees could buy a more expensive food (potatoes) and in order to inflation tha business had to buy expensive supplies in the factor market, while the rest of the world have to gain more money to consume the same amount of potatoes.